MongoDB vs PlanetScale for Solo Developers

Quick Comparison

MongoDB Overview

MongoDB is the leading document database. Instead of tables and rows, you store data as flexible JSON-like documents. This makes it easy to get started, especially if your data does not fit neatly into a relational model. MongoDB Atlas offers a managed cloud service with a free tier that covers small projects.

The developer experience is good. If you work with JavaScript, documents feel natural. The query language is intuitive for simple operations. MongoDB Compass provides a visual interface for browsing and querying data. For prototyping, the lack of required schema migrations means you can iterate on your data model without friction.

Where MongoDB falls short for solo developers is when your data is relational. Users have orders. Orders have products. Products belong to categories. Modeling these relationships in MongoDB requires denormalization, embedding, or application-level joins, all of which add complexity compared to SQL.

PlanetScale Overview

PlanetScale is a serverless MySQL platform built on Vitess, the same technology that powers YouTube's databases. Its standout feature is database branching, which lets you create branches of your database the same way you branch code. Schema changes happen on a branch, get reviewed, and merge into production with zero downtime.

The developer workflow is genuinely impressive. You create a schema change on a branch, PlanetScale shows you a diff of what will change, and you apply it without locking your production database. For teams that deploy frequently, this eliminates the fear of database migrations.

However, PlanetScale removed its free tier in 2024. The lowest plan starts at $39/month. For a solo developer with a side project, that is a meaningful monthly cost for a database. The platform also does not support foreign keys by default (a Vitess limitation), which is a notable constraint for relational data modeling.

Key Differences

NoSQL vs SQL. The fundamental architectural difference. MongoDB stores flexible documents. PlanetScale stores structured MySQL data in tables. For applications with clear entity relationships, SQL is more natural and efficient. For applications with varying document structures, MongoDB is more flexible. Most solo developer projects have relational data, which gives PlanetScale the edge here.

Free tier vs paid entry. MongoDB Atlas has a free tier that supports small applications. PlanetScale starts at $39/month. For a solo developer exploring an idea, MongoDB's free Atlas cluster lets you build and validate without spending money. PlanetScale requires financial commitment from day one.

Database branching vs schema flexibility. PlanetScale's branching workflow is unique and valuable for managing schema evolution. MongoDB sidesteps the problem entirely because it has no required schema. Both approaches address the pain of changing your data model, just from different angles. PlanetScale's approach is more disciplined. MongoDB's is more chaotic.

Foreign keys. PlanetScale does not support foreign keys by default due to Vitess constraints. This means referential integrity must be enforced at the application level. MongoDB also lacks foreign keys since it is a document database. In both cases, you lose database-level relationship enforcement, which is unusual for a MySQL-based platform like PlanetScale.

Querying power. PlanetScale gives you full MySQL SQL, including JOINs, subqueries, and aggregations. MongoDB uses its aggregation pipeline for complex queries. SQL is more widely known, easier to write for relational queries, and has better tooling support. MongoDB's aggregation pipeline is powerful but verbose.

Scaling approach. PlanetScale scales horizontally through Vitess sharding, which is automatic and managed. MongoDB Atlas also supports sharding but requires more configuration. Both handle scale well, but for a solo developer, you are unlikely to need sharding for a long time.

When to Choose MongoDB

• You want a free tier for prototyping and small projects
• Your data is genuinely document-oriented with varying structures
• You prefer the MongoDB query language and ecosystem
• Schema-free development speeds up your prototyping process
• Budget is a primary concern

When to Choose PlanetScale

• You want MySQL with professional-grade schema management
• Zero-downtime schema migrations are important to you
• You are comfortable paying $39/month for database hosting
• Your application needs relational data modeling (minus foreign keys)
• You want Vitess-level horizontal scaling built in

The Verdict

Neither is the ideal choice for most solo developers, but for different reasons. MongoDB's free tier makes it accessible for prototyping, but the document model adds complexity for relational data. PlanetScale has an excellent workflow, but the $39/month minimum is steep for a solo developer when alternatives like Neon and Supabase offer similar (or better) managed database experiences with free tiers.

If cost matters, MongoDB's free Atlas tier wins by default. If you want MySQL with great DX and can afford $39/month, PlanetScale is solid. But honestly, a solo developer in 2026 should look at Supabase or Neon first, as both offer more features, better free tiers, and PostgreSQL, which has stronger capabilities than either MongoDB or MySQL.