| Cover | Jun. 03, 2022 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Jun. 3, 2022 |
| Entity Registrant Name | PubMatic, Inc. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-39748 |
| Entity Tax Identification Number | 20-5863224 |
| Entity Address, Address Line One | 3 Lagoon Drive |
| Entity Address, Address Line Two | Suite 180 |
| Entity Address, City or Town | Redwood City |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 94065 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Class A Common Stock, par value $0.0001 per share |
| Trading Symbol | PUBM |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001422930 |
| Amendment Flag | false |
