| Document and Entity Information | May 23, 2024 |
| Cover [Abstract] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001866692 |
| Document Type | 8-K |
| Document Period End Date | May 23, 2024 |
| Entity Registrant Name | Amplitude, Inc. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-40817 |
| Entity Tax Identification Number | 45-3937349 |
| Entity Address, Address Line One | 201 Third Street |
| Entity Address, Address Line Two | Suite 200 |
| Entity Address, City or Town | San Francisco |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 94103 |
| City Area Code | (415) |
| Local Phone Number | 231-2353 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Class A Common Stock, $0.00001 par value per share |
| Trading Symbol | AMPL |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
