QuickLinks -- Click here to rapidly navigate through this document
Exhibit 31.1
SIZMEK INC. AND SUBSIDIARIES
CERTIFICATION PURSUANT TO RULE 13a-14(a)/15d-14(a)
I, Neil H. Nguyen, certify that:
- 1.
- I have reviewed this Amendment No. 1 to the annual report on Form 10-K of Sizmek Inc.;
- 2.
- Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;
| | |
| Date: April 30, 2015 | | /s/ NEIL H. NGUYEN
Neil H. Nguyen
President and Chief Executive Officer |
QuickLinks
SIZMEK INC. AND SUBSIDIARIES
