THESE SECURITIES HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933 AS
AMENDED, OR ANY STATE SECURITIES LAWS. THEY MAY NOT BE SOLD, OFFERED FOR SALE, 
PLEDGED, OR HYPOTHECATED IN THE ABSENCE OF AN EFFECTIVE REGISTRATION STATEMENT
RELATED THERETO OR AN OPINION OF COUNSEL (WHICH MAY BE COMPANY COUNSEL) 
REASONABLY SATISFACTORY TO THE COMPANY THAT SUCH REGISTRATION IS NOT REQUIRED
UNDER THE SECURITIES ACT OF 1933, AS AMENDED, OR ANY APPLICABLE STATE 
SECURITIES LAWS.

                               WARRANT AGREEMENT

         To Purchase Shares of Series A Convertible Preferred Stock of

                                 ALLAIRE CORP.

        Originally Dated as of December 30, 1996 (the "Effective Date")
                         Re-Issued as of August 21, 1998

     WHEREAS, Allaire Corp., a Minnesota corporation (the "Company") entered
into a Master Lease Agreement dated as of December 30, 1996, Equipment Schedule
No. VL-1 dated as of December 30, 1996, and related Summary Equipment Schedules
(collectively, the "Leases") with Comdisco, Inc., a Delaware corporation (the
"Warrantholder"); and

     WHEREAS, in consideration for such Leases, the Company entered into a
Warrant Agreement dated as of December 30, 1996 (the "Original Warrant 
Agreement"), whereby the Company granted the Warrantholder the right to 
purchase 17,699 shares of its Series A Convertible Preferred Stock; and

     WHEREAS, pursuant to and in accordance with the Original Warrant 
Agreement, the Warrantholder has transferred to Gregory Stento, effective as of
August 21, 1998, the Warrantholder's rights under the Original Warrant Agreement
with respect to the purchase of 1,970 shares of the Company's Series A 
Convertible Preferred Stock (the "Warrant Transfer"); and

     WHEREAS, the Company and the Warrantholder acknowledge the Warrant Transfer
and, accordingly, the Company is reissuing, as of August 21, 1998, the Warrant
provided for in the Original Warrant Agreement, and the Company and the
Warrantholder are entering into this Warrant Agreement to reflect the Warrant
Transfer and the Warrantholder's right to purchase 15,729 shares of Series A
Convertible Preferred Stock ("Preferred Stock");

     NOW, THEREFORE, in consideration of the Warrantholder executing and
delivering such Leases and in consideration of mutual covenants and agreements
contained herein, the Company and Warrantholder agree as follows:

1.   GRANT OF THE RIGHT TO PURCHASE PREFERRED STOCK.
     -----------------------------------------------

     (a)  The Company hereby grants to the Warrantholder, and the Warrantholder 
is entitled, upon the terms and subject to the conditions hereinafter set forth,
to subscribe to and purchase, from the Company, Fifteen Thousand Seven Hundred
Twenty-Nine (15,729) fully paid and non-assessable shares of the Company's 
Preferred Stock at a purchase price of $4.52 per share (the "Exercise Price").
The number and Exercise Price of such shares are subject to adjustment as 
provided in Section 8 hereof.

     (b)  Upon mandatory conversion of the Preferred Stock pursuant to the terms
set forth in the Company's Certificate of Incorporation, as amended (the 
"Mandatory Conversion"), the Warrantholder shall thereafter be entitled to 
receive, upon exercise of the Warrant, the number of shares of Common Stock


equivalent to that which would have been issuable if the Warrantholder had 
exercised the Warrant immediately prior to the Mandatory Conversion. In any
such case, appropriate adjustment (as determined by the Company's Board of
Directors) shall be made in the application of the provisions of this Warrant
Agreement with respect to the rights and interest of the Warrantholder after
the Mandatory Conversion to the end that the provision of this Warrant
Agreement (including adjustments of the Exercise Price and number of shares of
Common Stock purchasable) shall be applicable to the greatest extent possible.

2.   TERM OF THE WARRANT AGREEMENT.
     ------------------------------

     Except as otherwise provided for herein, the term of this Warrant 
Agreement and the right to purchase Preferred Stock as granted herein shall
commence on the Effective Date and shall be exercisable for a period of (i) ten
(10) years from the Effective Date or (ii) five (5) years from the effective 
date of the Company's initial public offering, whichever is shorter.

3.   EXERCISE OF THE PURCHASE RIGHTS.
     --------------------------------

     The purchase rights set forth in this Warrant Agreement are exercisable
by the Warrantholder, in whole or in part, at any time, or from time to time,
prior to the expiration of the term set forth in Section 2 above, by tendering
to the Company at its principal office a notice of exercise in the form 
attached hereto as Exhibit I (the "Notice of Exercise"), duly completed and
executed. Promptly upon receipt of the Notice of Exercise and the payment of 
the purchase price in accordance with the terms set forth below, and in no event
later than twenty-one (21) days thereafter, the Company shall issue to the 
Warrantholder a certificate for the number of shares of Preferred Stock 
purchased and shall execute the acknowledgment of exercise in the form attached
hereto as Exhibit II (the "Acknowledgment of Exercise") indicating the number
of shares which remain subject to future purchases, if any.

     The Exercise Price may be paid at the Warrantholder's election either (i) 
by cash or check, or (ii) by surrender of Warrants ("Net Issuance") as 
determined below. If the Warrantholder elects the Net Issuance method, the
Company will issue Preferred Stock in accordance with the following formula:


          X = Y(A-B)
              ------
                 A

 Where: X = the number of shares of Preferred Stock to be issued to the 
            Warrantholder.

        Y = the number of shares of Preferred Stock requested to be exercised 
            under this Warrant Agreement.

        A = the fair market value of one (1) share of Preferred Stock.

        B = the Exercise Price.

     For purposes of the above calculation, current fair market value of 
Preferred Stock shall mean with respect to each share of Preferred Stock.

     (i)  if the exercise is in connection with an initial public offering of
     the Company's Common Stock, and if the Company's Registration Statement
     relating to such public offering has been declared effective by the SEC,
     then the fair market value per share shall be the product of (x) the
     initial "Price to Public" specified in the final prospectus with respect
     to the offering and (y) the number of shares of Common Stock into which
     each share of Preferred Stock is convertible at the time of such exercise;

     (ii) if this Warrant is exercised after, and not in connection with the
     Company's initial public offering, and:


                                       2



          (a)  if traded on a securities exchange, the fair market value shall
          be deemed to be the product of (x) the average of the closing prices
          over a twenty-one (21) day period ending three days before the day
          the current fair market value of the securities is being determined
          and (y) the number of shares of Common Stock into which each share of
          Preferred Stock is convertible at the time of such exercise; or

          (b)  if actively traded over-the-counter, the fair market value shall
          be deemed to be the product of (x) the average of the closing bid and
          asked prices quoted on the NASDAQ system (or similar system) over the
          twenty-one (21) day period ending three days before the day the 
          current fair market value of the securities is being determined and
          (y) the number of shares of Common Stock into which each share of
          Preferred Stock is convertible at the time of such exercise;

     (iii)  if at any time the Common Stock is not listed on any securities
     exchange or quoted in the NASDAQ System or the over-the-counter market, 
     the current fair market value of Preferred Stock shall be the product of
     (x) the highest price per share which the Company could obtain from a 
     willing buyer (not a current employee or director) for shares of Common
     Stock sold by the Company, from authorized but unissued shares, as
     determined in good faith by its Board of Directors and (y) the number of
     shares of Common Stock into which each share of Preferred Stock is 
     convertible at the time of such exercise, unless the Company shall become
     subject to a merger, acquisition or other consolidation pursuant to which
     the Company is not the surviving party, in which case the fair market 
     value of Preferred Stock shall be deemed to be the value received by the
     holders of the Company's Preferred Stock on a common equivalent basis
     pursuant to such merger or acquisition.

     Upon partial exercise by either cash or Net Issuance, the Company shall
promptly issue an amended Warrant Agreement representing the remaining number
of shares purchasable hereunder. All other terms and conditions of such amended
Warrant Agreement shall be identical to those contained herein, including, but
not limited to the Effective Date hereof.

4.   RESERVATION OF SHARES.
     ----------------------

     (a) Authorization and Reservation of Shares. During the term of this
Warrant Agreement, the Company will at all times have authorized and reserved a
sufficient number of shares of its Preferred Stock to provide for the exercise
of the rights to purchase Preferred Stock as provided for herein.

     (b) Registration or Listing. If any shares of Preferred Stock required to
be reserved hereunder require registration with or approval of any governmental
authority under any Federal or State law (other than any registration under the
1933 Act, as then in effect, or any similar Federal statute then enforced, or
any state securities law,), or listing on any domestic securities exchange,
before such shares may be issued upon exercise (except to the extent that the
imposition of such requirement is due to inaccuracy, either on the Effective
Date or at the time of exercise, in the Warrantholder's representations and
warranties herein), the Company will, at its expense and as expeditiously as
possible, use its best efforts to cause such shares to be duly registered,
listed or approved for listing on such domestic securities exchange, as the case
may be.

5.   NO FRACTIONAL SHARES OR SCRIP.
     ------------------------------

     No fractional shares or scrip representing fractional shares shall be
issued upon the exercise of the Warrant, but in lieu of such fractional shares
the Company shall make a cash payment therefor upon the basis of the Exercise
Price then in effect.

6.   NO RIGHTS AS SHAREHOLDER.
     -------------------------

     This Warrant Agreement does not entitle the Warrantholder to any voting
rights or other rights as a shareholder of the Company prior to the exercise of
the Warrant.

                                       3


7.   WARRANTHOLDER REGISTRY.
     -----------------------

     The Company shall maintain a registry showing the name and address of the
registered holder of this Warrant Agreement.

8.   ADJUSTMENT RIGHTS.
     ------------------

     The purchase price per share and the number of shares of Preferred Stock
purchasable hereunder are subject to adjustment, as follows:

         (a) Merger and Sale of Assets. If at any time there shall be a capital
reorganization of the shares of the Company's stock (other than a combination,
reclassification, exchange or subdivision of shares otherwise provided for
herein), or a merger or consolidation of the Company with or into another
corporation whether or not the Company is the surviving corporation, or the sale
of all or substantially all of the Company's properties and assets to any other
person (hereinafter referred to as a "Merger Event"), then, as a part of such
Merger Event, lawful provision shall be made so that the Warrantholder shall
thereafter be entitled to receive, upon exercise of the Warrant, the number of
shares of Preferred Stock or other securities of the successor corporation
resulting from such Merger Event, equivalent to that which would have been
issuable if Warrantholder had exercised this Warrant immediately prior to the
Merger Event. In any such case, appropriate adjustment (as determined in good
faith by the Company's Board of Directors) shall be made in the application of
the provisions of this Warrant Agreement with respect to the rights and interest
of the Warrantholder after the Merger Event to the end that the provisions of
this Warrant Agreement (including adjustments of the Exercise Price and number
of shares of Preferred Stock purchasable) shall be applicable to the greatest
extent possible.

         (b) Reclassification of Shares. If the Company at any time shall, by
combination, reclassification, exchange or subdivision of securities or
otherwise, change any of the securities as to which purchase rights under this
Warrant Agreement exist into the same or a different number of securities of any
other class or classes, this Warrant Agreement shall thereafter represent the
right to acquire such number and kind of securities as would have been issuable
as the result of such change with respect to the securities which were subject
to the purchase rights under this Warrant Agreement immediately prior to such
combination, reclassification, exchange, subdivision or other change.

         (c) Subdivision or Combination of Shares. If the Company at any time
shall combine or subdivide its Preferred Stock, the Exercise Price shall be
proportionately decreased in the case of a subdivision, or proportionately
increased in the case of a combination.

         (d) Stock Dividends. If the Company at any time shall pay a dividend
payable in, or make any other distribution (except any distribution specifically
provided for in the foregoing subsections (a) or (b)) of the Company's stock,
then the Exercise Price shall be adjusted, from and after the record date of
such dividend or distribution, to that price determined by multiplying the
Exercise Price in effect immediately prior to such record date by a fraction (i)
the numerator of which shall be the total number of all shares of the Company's
stock outstanding immediately prior to such dividend or distribution, and (ii)
the denominator of which shall be the total number of all shares of the
Company's stock outstanding immediately after such dividend or distribution. The
Warrantholder shall thereafter be entitled to purchase, at the Exercise Price
resulting from such adjustment, the number of shares of Preferred Stock
(calculated to the nearest whole share) obtained by multiplying the Exercise
Price in effect immediately prior to such adjustment by the number of shares of
Preferred Stock issuable upon the exercise hereof immediately prior to such
adjustment and dividing the product thereof by the Exercise Price resulting from
such adjustment.

         (e) Right to Purchase Additional Stock. If, the Warrantholder's total
cost of equipment leased pursuant to the Leases exceeds $1,000,000,
Warrantholder shall have the right to purchase from the Company, at the Exercise
Price (adjusted as set forth herein), an additional number of shares, which
number

                                       4


shall be determined by (i) multiplying the amount by which the
Warrantholder's total equipment cost exceeds $1,000,000 by 8%, and (ii) dividing
the product thereof by the Exercise Price per share referenced above.

         (f) Antidilution Rights. Additional antidilution rights applicable to
the Preferred Stock purchasable hereunder are as set forth in the Company's
Article of Incorporation and Statement of Designation for the Preferred Stock,
as the same may be amended from time to time, a true and complete copy of which
is attached hereto as Exhibit _ (the "Charter"). The Company shall promptly
provide the Warrantholder with any restatement, amendment, modification or
waiver of the Charter. The Company shall provide Warrantholder with prior
written notice of any issuance of its stock or other equity security to occur
after the Effective Date of this Warrant, which notice shall include (a) the
price at which such stock or security is to be sold, (b) the number of shares to
be issued, and (c) such other information as necessary for Warrantholder to
determine if a dilutive event has occurred.

         (g) Notice of Adjustments. If: (i) the Company shall declare any
dividend or distribution upon its stock, whether in cash, property, stock or
other securities; (ii) the Company shall offer for subscription prorata to the
holders of any class of its Preferred or other convertible stock any additional
shares of stock of any class or other rights; (iii) there shall be any Merger
Event; (iv) there shall be an initial public offering; or (v) there shall be any
voluntary dissolution, liquidation or winding up of the Company; then, in
connection with each such event, the Company shall send to the Warrantholder:
(A) at least twenty (20) days' prior written notice of the date on which the
books of the Company shall close or a record shall be taken for such dividend,
distribution, subscription rights (specifying the date on which the holders of
Preferred Stock shall be entitled thereto) or for determining rights to vote in
respect of such Merger Event, dissolution, liquidation or winding up; (B) in the
case of any such Merger Event, dissolution, liquidation or winding up, at least
twenty (20) days' prior written notice of the date when the same shall take
place (and specifying the date on which the holders of Preferred Stock shall be
entitled to exchange their Preferred Stock for securities or other property
deliverable upon such Merger Event, dissolution, liquidation or winding up); and
(C) in the case of a public offering, the Company shall give the Warrantholder
at least twenty (20) days written notice prior to the effective date thereof.

         Each such written notice shall set forth, in reasonable detail, (i) the
event requiring the adjustment, (ii) the amount of the adjustment, (iii) the
method by which such adjustment was calculated, (iv) the Exercise Price, and (v)
the number of shares subject to purchase hereunder after giving effect to such
adjustment, and shall be given by first class mail, postage prepaid, addressed
to the Warrantholder, at the address as shown on the books of the Company.

         (h) Timely Notice. Failure to timely provide such notice required by
subsection (g) above shall entitle Warrantholder to retain the benefit of the
applicable notice period notwithstanding anything to the contrary contained in
any insufficient notice received by Warrantholder. The notice period shall begin
on the date Warrantholder actually receives a written notice containing all the
information specified above.

9.   REPRESENTATIONS, WARRANTIES AND COVENANTS OF THE COMPANY.
     ---------------------------------------------------------

         (a) Reservation of Preferred Stock. The Preferred Stock issuable upon
exercise of the Warrantholder's rights has been duly and validly reserved and,
when issued in accordance with the provisions of this Warrant Agreement, will be
validly issued, fully paid and non-assessable, and will be free of any taxes,
liens, charges or encumbrances of any nature whatsoever, provided, however, that
the Preferred Stock issuable pursuant to this Warrant Agreement may be subject
to restrictions on transfer under state and/or Federal securities laws. The
Company has made available to the Warrantholder true, correct and complete
copies of its Charter and Bylaws, as amended. The issuance of certificates for
shares of Preferred Stock upon exercise of the Warrant Agreement shall be made
without charge to the Warrantholder for any issuance tax in respect thereof, or
other cost incurred by the Company in connection with such exercise and the
related issuance of shares of Preferred Stock. The Company shall not be required
to pay any tax which may be payable in respect of any transfer involved and the
issuance and delivery of any certificate in a name other than that of the
Warrantholder.


                                       5




     (b) Due Authority. The execution and delivery by the Company of this
Warrant Agreement and the performance of all obligations of the Company
hereunder, including the issuance to Warrantholder of the right to acquire the
shares of Preferred Stock, have been duly authorized by all necessary corporate
action on the part of the Company, and the Leases and this Warrant Agreement are
not inconsistent with the Company's Charter or Bylaws, do not contravene any law
or governmental rule, regulation or order applicable to it, do not and will not
contravene any provision of, or constitute a default under, any indenture,
mortgage, contract or other instrument to which it is a party or by which it is
bound, and the Leases and this Warrant Agreement constitute legal, valid and
binding agreements of the Company, enforceable in accordance with their
respective terms.

     (c) Consents and Approvals. No consent or approval of, giving of notice to,
registration with, or taking of any other action in respect of any state,
Federal or other governmental authority or agency is required with respect to
the execution, delivery and performance by the Company of its obligations under
this Warrant Agreement, except for the filing of notices pursuant to Regulation
D under the 1933 Act and any filing required by applicable state securities law,
which filings will be effective by the time required thereby.

     (d) Issued Securities. All issued and outstanding shares of Common Stock,
Preferred Stock or any other securities of the Company have been duly authorized
and validly issued and are fully paid and nonassessable. All outstanding shares
of Common Stock, Preferred Stock and any other securities were issued in full
compliance with all Federal and state securities laws.

     (e) Insurance. The Company has in full force and effect insurance policies,
with extended coverage, insuring the Company and its property and business
against such losses and risks, and in such amounts, as are customary for
corporations engaged in a similar business and similarly situated and as
otherwise may be required pursuant to the terms of any other contract or
agreement.

     (f) Exempt Transaction. Subject to the accuracy of the Warrantholder's
representations in Section 10 hereof, the issuance of the Preferred Stock upon
exercise of this Warrant will constitute a transaction exempt from (i) the
registration requirements of Section 5 of the 1933 Act, in reliance upon Section
4(2) thereof, and (ii) the qualification requirements of the applicable state
securities laws.

     (g) Compliance with Rule 144. At the written request of the Warrantholder,
who proposes to sell Preferred Stock issuable upon the exercise of the Warrant
in compliance with Rule 144 promulgated by the Securities and Exchange
Commission, the Company shall furnish to the Warrantholder, within ten days
after receipt of such request, a written statement confirming the Company's
compliance with the filing requirements of the Securities and Exchange
Commission as set forth in such Rule, as such Rule may be amended from time to
time.

10.  REPRESENTATIONS AND COVENANTS OF THE WARRANTHOLDER.
     ---------------------------------------------------

     This Warrant Agreement has been entered into by the Company in reliance
upon the following representations and covenants of the Warrantholder:

     (a) Investment Purpose. The right to acquire Preferred Stock or the
Preferred Stock issuable upon exercise of the Warrantholder's rights contained
herein will be acquired for investment and not with a view to the sale or
distribution of any part thereof, and the Warrantholder has no present intention
of selling or engaging in any public distribution of the same except pursuant to
a registration or exemption.

     (b) Private Issue. The Warrantholder understands (i) that the Preferred
Stock issuable upon exercise of this Warrant is not registered under the 1933
Act or qualified under applicable state securities laws on the ground that the
issuance contemplated by this Warrant Agreement will be exempt from the
registration and qualifications requirements thereof, and (ii) that the
Company's reliance on such exemption is predicated on the representations set
forth in this Section 10.

                                       6



     (c) Disposition Warrantholder's Rights. In no event will the Warrantholder
make a disposition of any of its rights to acquire Preferred Stock or Preferred
Stock issuable upon exercise of such rights unless and until (i) it shall have
notified the Company of the proposed disposition, and (ii) if requested by the
Company, it shall have furnished the Company with an opinion of counsel (which
counsel may either be inside or outside counsel to the Warrantholder)
satisfactory to the Company and its counsel to the effect that (A) appropriate
action necessary for compliance with the 1933 Act has been taken, or (B) an
exemption from the registration requirements of the 1933 Act is available.
Notwithstanding the foregoing, the restrictions imposed upon the transferability
of any of its rights to acquire Preferred Stock or Preferred Stock issuable on
the exercise of such rights do not apply to transfers from the beneficial owner
of any of its aforementioned securities to its nominee or from such nominee to
its beneficial owner, and shall terminate as to any particular share of
Preferred Stock when (1) such security shall have been effectively registered
under the 1933 Act and sold by the holder thereof in accordance with such
registration or (2) such security shall have been sold without registration in
compliance with Rule 144 under the 1933 Act, or (3) a letter shall have been
issued to the Warrantholder at its request by the staff of the Securities and
Exchange Commission or a ruling shall have been issued to the Warrantholder at
its request by such Commission stating that no action shall be recommended by
such staff or taken by such Commission, as the case may be, if such security is
transferred without registration under the 1933 Act in accordance with the
conditions set forth in such letter or ruling and such letter or ruling
specifies that no subsequent restrictions on transfer are required. Whenever the
restrictions imposed hereunder shall terminate, as hereinabove provided, the
Warrantholder or holder of a share of Preferred Stock then outstanding as to
which such restrictions have terminated shall be entitled to receive from the
Company, without expense to such holder, one or more new certificates for the
Warrant or for such shares of Preferred Stock not bearing any restrictive
legend.

     (d) Financial Risk. The Warrantholder has such knowledge and experience in
financial and business matters as to be capable of evaluating the merits and
risks of its investment. and has the ability to bear the economic risks of its
investment.

     (e) Risk of No Registration, The Warrantholder understands that if the
Company does not register with the Securities and Exchange Commission pursuant
to Section 12 of the 1934 Act (the "1934 Act"), or file reports pursuant to
Section 15(d), of the 1934 Act, or if a registration statement covering the
securities under the 1933 Act is not in effect when it desires to sell (i) the
rights to purchase Preferred Stock pursuant to this Warrant Agreement, or (ii)
the Preferred Stock issuable upon exercise of the right to purchase, it may be
required to hold such securities for an indefinite period. The Warrantholder
also understands that any sale of its rights of the Warrantholder to purchase
Preferred Stock or Preferred Stock which might be made by it in reliance upon
Rule 144 under the 1933 Act may be made only in accordance with the terms and
conditions of that Rule.

     (f) Accredited Investor. Warrantholder is an "accredited investor" within
the meaning of the Securities and Exchange Rule 501 of Regulation D, as
presently in effect.

11.  REGISTRATION RIGHTS AGREEMENT.
     ------------------------------

     The Warrantholder shall be entitled to the registration rights afforded to,
and be subject to the obligations of, other holders of the Series A Convertible
Preferred Stock pursuant to that certain Registration Rights Agreement dated
June 18, 1996, a copy of which has been provided to the Warrantholder. As soon
as practicable following the execution of this Agreement, such Registration
Rights Agreement shall be amended to add the Warrantholder as a party.

12.  TRANSFERS.
     ----------

     Subject to the terms and conditions contained in Section 10 hereof and the
restrictive legend first set forth above, this Warrant Agreement and all rights
hereunder are transferable in whole or in part by the Warrantholder and any
successor transferee, provided, however, in no event shall the number of
transfers of the rights and interests in all of the Warrants exceed three (3)
transfers. The transfer shall be recorded on the books of the Company upon
receipt by the Company of a notice of transfer in the form attached hereto as

                                       7


Exhibit III (the "transfer Notice"), at its principal offices and the payment to
the Company of all transfer taxes and other governmental charges imposed on such
transfer.

13.  MISCELLANEOUS.
     --------------

     (a) Effective Date. The provisions of this Warrant Agreement shall be
construed and shall be given effect in all respects as if it had been executed
and delivered by the Company on the date hereof. This Warrant Agreement shall be
binding upon any successors or assigns of the Company.

     (b) Attorney's Fees. In any litigation, arbitration or court proceeding
between the Company and the Warrantholder relating hereto, the prevailing party
shall be entitled to attorneys' fees and expenses and all costs of proceedings
incurred in enforcing this Warrant Agreement.

     (c) Governing Law. This Warrant Agreement shall be governed by and
construed for all purposes under and in accordance with the laws of the State of
Illinois.

     (d) Counterparts. This Warrant Agreement may be executed in two or more
counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.

     (e) Notices. Any notice required or permitted hereunder shall be given in
writing and shall be deemed effectively given upon personal delivery, facsimile
transmission (provided that the original is sent by personal delivery or mail as
hereinafter set forth) or seven (7) days after deposit in the United States
mail, by registered or certified mail, addressed (i) to the Warrantholder at
6111 North River Road, Rosemont, Illinois 60018, attention: James Labe, Venture
Group, cc: Legal Department, attention: General Counsel, (and/or, if by
facsimile, (847) 518-5465 and (847) 518-5088) and (ii) to the Company at One
Alewife Center, Third Floor, Cambridge, Massachusetts 02140, attention: Joe
Baker (and/or if by facsimile, (617) 761-2001) or at such other address as any
such party may subsequently designate by written notice to the other party.

     (f) Remedies. In the event of any default hereunder, the non-defaulting
party may proceed to protect and enforce its rights either by suit in equity
and/or by action at law, including but not limited to an action for damages as a
result of any such default, and/or an action for specific performance for any
default where Warrantholder will not have an adequate remedy at law and where
damages will not be readily ascertainable. The Company expressly agrees that it
shall not oppose an application by the Warrantholder or any other person
entitled to the benefit of this Agreement requiring specific performance of any
or all provisions hereof or enjoining the Company from continuing to commit any
such breach of this Agreement.

     (g) No Impairment of Rights. The Company will not, by amendment of its
Charter or through any other means, avoid or seek to avoid the observance or
performance of any of the terms of this Warrant, but will at all times in good
faith assist in the carrying out of all such terms and in the taking of all such
actions as may be necessary or appropriate in order to protect the rights of the
Warrantholder against impairment.

     (h) Survival. The representations, warranties. covenants and conditions of
the respective parties contained herein or made pursuant to this Warrant
Agreement shall survive the execution and delivery of this Warrant Agreement.

     (i) Severability. In the event any one or more of the provisions of this
Warrant Agreement shall for any reason be held invalid, illegal or
unenforceable, the remaining provisions of this Warrant Agreement shall be
unimpaired, and the invalid, illegal or unenforceable provision shall be
replaced by a mutually acceptable valid, legal and enforceable provision, which
comes closest to the intention of the parties underlying the invalid, illegal or
unenforceable provision.

     (j) Amendments. Any provision of this Warrant Agreement may be amended by a
written instrument signed by the Company and by the Warrantholder.

                                       8



     (k)  Additional Documents.    The Company, upon execution of this
Warrant Agreement, shall provide the Warrantholder with certified resolutions
with respect to the representations, warranties and covenants set forth in
subparagraphs (a) through (d), (f) and (g) of Section 9 above. If the purchase
price for the Leases referenced in the preamble of this Warrant Agreement
exceeds $1,000,000, the Company will also provide Warrantholder with an opinion
from the Company's counsel with respect to those same representations, 
warranties and covenants. The Company shall also supply such other documents
as the Warrantholder may from time to time reasonably request.

     IN WITNESS WHEREOF, the parties hereto have caused this Warrant Agreement
to be executed by its officers thereunto duly authorized as of the Effective
Date.

                                        Company: ALLAIRE CORP.


                                        By:    /s/ David Gerth
                                               -------------------------------

                                        Title: Chief Financial Officer
                                               ------------------------------



                                        Warrantholder: COMDISCO, INC.


                                        By:    /s/ John J. Vosecly
                                               ------------------------------

                                        Title: Executive Vice President & CFO
                                               -------------------------------


                                       9




                                    EXHIBIT I

                               NOTICE OF EXERCISE

To: ________________________________


(1)  The undersigned Warrantholder hereby elects to purchase __________________
     shares of the Series A Convertible Preferred Stock of Allaire Corp.,
     pursuant to the terms of the Warrant Agreement dated the 21st day of
     August, 1998 (the "Warrant Agreement") between Allaire Corp. and the
     Warrantholder, and tenders herewith payment of the purchase price for such
     shares in full, together with all applicable transfer taxes, if any.

(2)  In exercising its rights to purchase the Series A Convertible Preferred
     Stock of Allaire Corp., the undersigned hereby confirms and acknowledges
     the investment representations and warranties made in Section 10 of the
     Warrant Agreement.

(3)  Please issue a certificate or certificates representing said shares of
     Series A Convertible Preferred Stock in the name of the undersigned or in
     such other name as is specified below.

___________________________________
(Name)

___________________________________
(Address) 


Warrantholder: COMDISCO, INC.

By: _______________________________

Title:_____________________________

Date: _____________________________









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                                   EXHIBIT II

                           ACKNOWLEDGMENT OF EXERCISE

     The undersigned _________________________, hereby acknowledge receipt of
the "Notice of Exercise" from Comdisco, Inc., to purchase _____ shares of the
Series A Convertible Preferred Stock of Allaire Corp., pursuant to the terms of
the Warrant Agreement, and further acknowledges that ______________ shares
remain subject to purchase under the terms of the Warrant Agreement.



                                             Company:


                                             By:__________________________

                                             Title:_______________________

                                             Date: _______________________


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                                   EXHIBIT III

                                TRANSFER NOTICE

(To transfer or assign the foregoing Warrant Agreement execute this form and
supply required information. Do not use this form to purchase shares.)

     FOR VALUE RECEIVED, the foregoing Warrant Agreement and all rights
evidenced thereby are hereby transferred and assigned to

______________________________________________________________________________
(Please Print)

whose address is______________________________________________________________

______________________________________________________________________________


               Dated _______________________________________


               Holder's Signature ___________________________


               Holder's Address______________________________

               ______________________________________________


Signature Guaranteed: ______________________________________________________


   NOTE:  The signature to this Transfer Notice must correspond with the name
          as it appears on the face of the Warrant Agreement, without alteration
          or enlargement or any change whatever. Officers of corporations and
          those acting in a fiduciary or other representative capacity should
          file proper evidence of authority to assign the foregoing Warrant
          Agreement.


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