Comparison

MongoDB vs Firebase

MongoDB and Firebase both land on Depends.

MongoDB

Depends

Confidence: Medium

Buy MongoDB if you have developers and document-shaped, fast-changing, high-write data.

Depends

Confidence: Medium

Buy it if you're a small team shipping a mobile or web app fast and you set billing alerts on day one.

MongoDB versus Firebase
Compare	MongoDB	Firebase
Verdict	Depends	Depends
Best for	Document-heavy, fast-changing schemas	Mobile app MVPs
Who it's not for	Relational, join-heavy data . reviewers say Postgres wins	Apps needing complex relational queries and joins
Privacy	Active threat surface: critical 2025 memory-disclosure CVE reportedly exploited in the wild, plus a 2023 customer-data incident; patches released.^⁷	Google-backed and generally safe when configured correctly; SDK CVEs exist, and misconfigured rules have caused massive public leaks.
Support quality	Trustpilot cites 'big company with 0 support'	No evidence in sources reviewed
Public sentiment	Users love the flexibility and quick start for document data, but commonly gripe about support, scaling costs, and default to Postgres for relational work.	Users praise the quick setup and free auth but repeatedly warn about surprise bills and security-rule pitfalls.¹²
Biggest gotcha	MongoBleed (CVE-2025-14847): exposed or misconfigured instances were targeted; patch fast and audit exposure.	Blaze pay-as-you-go can spike hard; Reddit documents bills skyrocketing from one bad loop¹⁵