DevFixes
DevFixes Labs

Learn debugging by doing.

Practice solving realistic software failures inside safe, interactive environments. Observe the evidence, form a hypothesis, apply the fix, and verify the result.

11labs
114scenarios
0%your progress
Choose an environment

Start with the stack you use.

safe simulator
Python Lab

Tracebacks, imports, environments, and the habits that make Python failures predictable.

Tracebackspipvirtual environments
Beginner45 min12 challenges
0% complete
safe simulator
React Lab

Find render loops, state mistakes, hydration mismatches, and data-loading bugs.

Stateeffectscomponents
Beginner50 min10 challenges
0% complete
safe simulator
JavaScript Lab

Debug runtime exceptions, async boundaries, and unsafe assumptions in browser code.

Runtime errorsasync codedata states
Beginner40 min11 challenges
0% complete
safe simulator
Node.js Lab

Repair package scripts, environment variables, ports, and broken service startup.

npmconfigurationservers
Beginner55 min12 challenges
0% complete
safe simulator
Docker Lab

Investigate images, containers, networks, volumes, compose, and deployment failures.

Composeportscontainers
Intermediate60 min10 challenges
0% complete
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Git Lab

Practice conflicts, rebases, detached HEAD states, and safe recovery workflows.

Conflictshistoryrecovery
Intermediate50 min10 challenges
0% complete
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VS Code Lab

Use an editor-like workspace to diagnose interpreters, extensions, and Problems panel noise.

InterpretersPylancesettings
Beginner45 min9 challenges
0% complete
safe simulator
Linux Lab

Work through permissions, processes, networking, SSH, and shell failures in a safe terminal.

Bashpermissionsprocesses
Beginner55 min12 challenges
0% complete
safe simulator
Database Lab

Separate connection, authentication, migration, schema, and query failures.

PostgreSQLmigrationsschema
Intermediate65 min11 challenges
0% complete
safe simulator
Cloud Lab

Recover serverless, deployment, permissions, and production reliability incidents.

Lambdaobservabilitylimits
Advanced70 min8 challenges
0% complete
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AI Coding Lab

Debug local models, coding agents, extension setup, provider configuration, and quotas.

Ollamamodelsagent setup
Beginner40 min9 challenges
0% complete
The debugging loop

Professional habits, made playable.

01Observe

Read the terminal, logs, code, and environment before touching the fix.

02Hypothesize

Use evidence to name the smallest likely root cause.

03Apply

Change one thing and keep a record of what you expected to happen.

04Verify

Run the check, interpret the output, and reflect on prevention.