| Cover - USD ($) $ in Millions | 12 Months Ended | | |
| Sep. 30, 2023 | Jan. 25, 2024 | Mar. 31, 2023 |
| Document Information [Line Items] | | | |
| Document Type | 10-K/A | | |
| Document Annual Report | true | | |
| Document Period End Date | Sep. 30, 2023 | | |
| Current Fiscal Year End Date | --09-30 | | |
| Document Transition Report | false | | |
| Securities Act File Number | 001-41571 | | |
| Entity Registrant Name | MariaDB plc | | |
| Entity Incorporation, State or Country Code | L2 | | |
| Entity Address, Address Line One | 699 Veterans Blvd | | |
| Entity Address, City or Town | Redwood City | | |
| Entity Address, State or Province | CA | | |
| Entity Address, Postal Zip Code | 94063 | | |
| City Area Code | 855 | | |
| Local Phone Number | 562-7423 | | |
| Entity Well-known Seasoned Issuer | No | | |
| Entity Voluntary Filers | No | | |
| Entity Current Reporting Status | Yes | | |
| Entity Interactive Data Current | Yes | | |
| Entity Filer Category | Non-accelerated Filer | | |
| Entity Small Business | true | | |
| Entity Emerging Growth Company | true | | |
| Entity Ex Transition Period | false | | |
| ICFR Auditor Attestation Flag | false | | |
| Document Financial Statement Error Correction | false | | |
| Entity Shell Company | false | | |
| Entity Public Float | | | $ 72.1 |
| Documents Incorporated by Reference | None | | |
| Entity Ordinary Shares Outstanding | | 67,749,429 | |
| Entity Central Index Key | 0001929589 | | |
| Document Fiscal Year Focus | 2023 | | |
| Document Fiscal Period Focus | FY | | |
| Amendment Flag | true | | |
| Amendment Description | EXPLANATORY NOTEWe are filing this Amendment No. 1 on Form 10-K/A, or this Amendment, to our Annual Report on Form 10-K for the fiscal year ended September 30, 2023 for the sole purpose of reporting the information required by Part III of Form 10-K. Our Annual Report on Form 10-K, or the Original Filing, was originally filed with the Securities and Exchange Commission, or the SEC, on December 29, 2023. Items 10 through 14 of Item III of Form 10-K are more limited than what is required to be included in the proxy statement to be filed in connection with our 2024 Annual General Meeting of Shareholders. Accordingly, the proxy statement to be filed at a later date will include additional information related to the topics herein and additional information not required by Items 10 through 14 of Item III of Form 10-K.This Amendment (i) amends and restates in their entirety Items 10, 11, 12, 13 and 14 of Part III of the Original Filing and (ii) deletes the reference on the cover of the Original Filing to the incorporation by reference of portions of the Company’s definitive proxy statement into Part III of the Original Filing. Pursuant to the SEC rules, Item 15 of Part IV has also been amended to contain the currently dated certificates from the Company’s principal executive officer and principal financial officer pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. The certificates of the Company’s principal executive officer and principal financial officer are attached to this Amendment as Exhibits 31.3 and 31.4. Because no financial statements have been included in this Amendment and this Amendment does not contain or amend any disclosure with respect to Items 307 and 308 of Regulation S-K, paragraphs 3, 4 and 5 of the certifications have been omitted. Additionally, we are not including the certificate under Section 906 of the Sarbanes-Oxley Act of 2002 as no financial statements are being filed with this Amendment.Other than with respect to the information contained herein with respect to Part III below, this Amendment does not change any of the information contained in the Original Filing. Other than as specifically set forth herein, we have not updated or amended the disclosures contained in the Original Filing to reflect events that have occurred since the date thereof. Accordingly, this Amendment should be read in conjunction with our Original Filing. Capitalized terms used but not defined herein shall have the meanings ascribed to them in the Original Filing. | | |
| Ordinary Shares | | | |
| Document Information [Line Items] | | | |
| Title of 12(b) Security | Ordinary Shares, nominal value $0.01 per share | | |
| Trading Symbol | MRDB | | |
| Security Exchange Name | NYSE | | |
| Warrants | | | |
| Document Information [Line Items] | | | |
| Title of 12(b) Security | Warrants, each whole warrant exercisable for one Ordinary Share at an exercise price of $11.50 per share | | |
| Trading Symbol | MRDBW | | |
| Security Exchange Name | NYSE | | |
