Opinion: Why MongoDB 8.0 Is a Bad Choice for New Web Apps

When starting a new web application in 2024, choosing the right database is one of the most consequential early decisions. MongoDB has long been a popular NoSQL option, but its latest 8.0 release doubles down on missteps that make it a poor fit for modern greenfield projects. Below, we break down the key reasons to skip MongoDB 8.0 for new web apps.

1. Unnecessary Operational Complexity

MongoDB 8.0 introduces several new features that add bloat without solving core pain points for small to mid-sized web apps. The new sharding automation tools, for example, require deep expertise to configure correctly, and default settings often lead to performance bottlenecks under moderate load. For teams without dedicated DevOps staff, managing a MongoDB 8.0 cluster adds hours of weekly overhead compared to managed relational databases like PlanetScale or Supabase.

Even basic tasks like schema validation (a long-requested feature) remain clunky in 8.0: the new JSON Schema integration requires writing verbose configuration files, and runtime errors for invalid data are non-obvious, leading to more debugging time for junior developers.

2. Poor Support for Relational Data

Most modern web apps need to model relationships between users, content, orders, and more. MongoDB’s document model forces developers to choose between embedding related data (leading to bloated documents and update anomalies) or referencing (requiring multiple round trips to the database, or complex application-side joins that hurt performance).

MongoDB 8.0’s new "relational lookup" features are a band-aid at best: they add latency, don’t support proper indexing across joined collections, and fail to match the performance of even basic SQL joins in PostgreSQL or MySQL. For new apps that may need to evolve their data model, this limitation is a dealbreaker.

3. Incomplete ACID Compliance for Critical Use Cases

While MongoDB has added multi-document ACID transactions in recent versions, 8.0 still falls short for workloads that require strict consistency. Transactions in MongoDB 8.0 have lower throughput than SQL alternatives, and they don’t support cross-shard transactions without significant performance penalties. For e-commerce, fintech, or any app handling user funds or sensitive data, this creates unnecessary risk.

Worse, MongoDB’s default read concern is still "local" for many operations, meaning developers have to explicitly configure stronger consistency levels for every critical query, increasing the chance of human error.

4. Hidden Costs and Vendor Lock-in

MongoDB’s pricing model for 8.0 has shifted further toward enterprise tiers, with key features like advanced monitoring, backup, and sharding support locked behind paywalls. For new startups, what starts as a free open-source deployment often balloons into thousands of dollars in monthly costs once the app scales to moderate traffic.

Additionally, MongoDB’s proprietary query language and driver ecosystem make it hard to migrate away if you outgrow the database. Unlike SQL, which has universal tooling and support, moving data out of MongoDB requires custom ETL pipelines and significant refactoring of application code.

5. Better Alternatives Are Available

For new web apps, there are far better options depending on your needs. If you need relational data support, PostgreSQL (with extensions like PostGIS or JSONB for NoSQL-like flexibility) is a far more mature, performant, and cost-effective choice. For NoSQL use cases, managed options like Firebase Firestore, AWS DynamoDB, or even newer document databases like FerretDB (which is MongoDB-compatible but open-source) avoid the pitfalls of MongoDB 8.0.

Even MongoDB’s own Atlas managed service can’t offset the core flaws of the 8.0 engine: you’re still paying for a database that’s harder to use, less performant, and more expensive than alternatives.

Conclusion

MongoDB 8.0 is a solution looking for a problem. For new web apps, it adds unnecessary complexity, limits your ability to model data correctly, and creates long-term cost and migration risks. Unless you have a very specific, MongoDB-shaped use case (like storing massive, unstructured IoT data with no relational needs), skip 8.0 entirely and choose a database that will grow with your app, not hold it back.