MySQL vs MongoDB for Solo Developers

Quick Comparison

MySQL Overview

MySQL is the most widely deployed open-source relational database in the world. It powers the LAMP stack, WordPress, and countless web applications. You store data in tables with defined columns, enforce relationships with foreign keys, and query everything with SQL. It is straightforward, proven, and supported by every hosting provider in existence.

For a solo developer, MySQL's strength is its simplicity and ubiquity. Setting up a MySQL database takes minutes. The documentation is extensive, the community is huge, and when you run into problems, someone has already solved them on Stack Overflow. Frameworks like Laravel, Rails, and Django all support MySQL out of the box.

MongoDB Overview

MongoDB stores data as flexible JSON-like documents in collections instead of rows in tables. There is no fixed schema. A document in the same collection can have different fields from its neighbors. This flexibility is MongoDB's core appeal, especially during the early stages when your data model is still evolving.

MongoDB Atlas provides a genuinely useful free tier with 512 MB of storage, shared clusters, and enough resources to run a real application. The Atlas interface is clean, and features like full-text search (Atlas Search), charts, and triggers are built in. For prototyping and early-stage development, MongoDB makes it easy to get started.

The aggregation pipeline replaces SQL joins and provides powerful data transformation, but it has a steep learning curve. Once you understand stages like $lookup, $unwind, and $group, you can do complex data processing, though it never feels as intuitive as SQL.

Key Differences

Schema flexibility is the headline difference. MySQL requires you to define your table structure before inserting data. Adding a column means running ALTER TABLE. MongoDB lets you store any document structure and change it freely. For a solo developer exploring an idea, this flexibility speeds up early development. But it also means your application code must handle documents that might be missing fields or have inconsistent types.

Joins and relationships favor MySQL. Relational data, things like users who have orders that contain products, is MySQL's strength. You define foreign keys, write JOIN queries, and the database enforces referential integrity. MongoDB has $lookup for joining collections, but it is slower, more complex, and does not enforce referential integrity. If your data is naturally relational, MySQL (or Postgres) is the better fit.

MongoDB is easier to start, harder to scale correctly. Throwing JSON documents into a collection is fast. But as your data grows, you need to think about indexes, schema validation, and data consistency. Without planning, MongoDB databases become a mess of inconsistent documents that are hard to query efficiently.

SQL skills are more transferable. MySQL, PostgreSQL, SQLite, PlanetScale, CockroachDB, Supabase, Neon. They all use SQL. Learning MySQL teaches you skills that work across the entire relational database ecosystem. MongoDB's query language and aggregation pipeline are unique to MongoDB.

Cost at scale diverges. MySQL is free and runs on any cheap VPS. MongoDB Atlas free tier is great for starting, but dedicated clusters start at $57/mo. Self-hosted MongoDB is free but requires more operational knowledge than self-hosted MySQL.

Data consistency is MySQL's advantage. MySQL enforces types, constraints, and foreign keys by default. If you try to insert a string into an integer column, it fails. MongoDB accepts whatever you send. For a solo developer without a QA team, having the database catch type errors and constraint violations is valuable.

When to Choose MySQL

• Your data is naturally relational (users, orders, products, categories)
• You want the database to enforce data integrity and types
• You are building with PHP/Laravel or WordPress
• You value SQL skills that transfer to other databases
• You want the cheapest possible hosting (every provider supports MySQL)

When to Choose MongoDB

• Your data model is genuinely document-oriented (CMS content, logs, IoT data)
• Your schema is changing rapidly during early development
• You need full-text search built into your database (Atlas Search)
• You want a free managed database tier for prototyping
• Your data does not have complex relational dependencies

The Verdict

Both score 7/10 for solo developers, and the right choice depends on your data. If your data has relationships (users own things, things belong to categories, transactions reference accounts), MySQL is the better fit. Relational databases exist because relational data is the most common type of data in web applications.

If your data is genuinely document-oriented, where each record is a self-contained blob that rarely references other records, MongoDB works well. Think content management systems, event logs, or configuration stores.

My honest take: most solo developers building web applications should reach for a relational database. And if you are choosing a relational database, PostgreSQL beats MySQL on features. But between MySQL and MongoDB specifically, pick whichever matches your data structure. Do not force relational data into documents, and do not force document data into tables.