Learning Center
Understand what AI is doing while you build
27 guides covering the parts of an AI-built application people meet when something stops working: requests, keys, access rules, deployments and the errors in between. Free to read, no account needed.
Browse by topic
AI Building
2What AI coding tools actually do when they write and wire up an application for you.
Troubleshooting
9Symptom-first guides: what the error means, what caused it, how to check, and how to know it is really fixed.
APIs
3Requests, responses, keys, status codes and the traffic between your app and everything else.
Databases
1Tables, queries, access rules and why the database is usually the thing that says no.
Authentication
1Who someone is, what they are allowed to do, and the difference that trips most people up.
Deployment
2What happens between your code and a working public URL, and where it tends to break.
GitHub
1Repositories, commits, branches and how AI tools use them on your behalf.
Security
3Keys, secrets, access rules and the mistakes that show up most often in generated code.
MCP
2The Model Context Protocol: how AI assistants are given access to tools and data.
AI Agents
1How a model goes from answering a question to taking actions in real systems.
Tools
1How the pieces of a modern AI-assisted stack fit together, and which piece owns which job.
Launch Guides
1The checks worth running before anyone else sees the thing you built.
Recently updated
- What actually happens when AI builds an app?A step-by-step account of what an AI building tool does between your sentence and a working page: planning, file writes, dependencies, database changes and deployment.
- How AI coding tools workInside an AI coding tool: the model, the context window, the tool calls, the build loop, and why the wrapper around the model matters as much as the model.
- How Lovable, GitHub, Vercel and Supabase work togetherFour tools, four jobs. Where your code lives, where it runs, where your data sits, and what moves between them when you ship a change.
- API keys explainedWhat an API key is, what it proves, why some keys are safe in a browser and others are not, and how to handle one without leaking it.
- How APIs work in AI-built applicationsRequests, responses, headers and status codes — explained through the calls an AI-generated app actually makes, and where those calls tend to go wrong.
- 401 vs 403 vs 404 vs 429 vs 500Five status codes that cover most failures in an AI-built app, what each one is really saying, and who has to fix it.
Reading is the start, not the point
MessyDev is the hands-on version of these guides: you break something, work out why, fix it, and check the fix. The first exercise is free and needs no account.