API debugging
How to debug an invalid JSON API response
Find why an API response cannot be parsed as JSON, distinguish syntax errors from HTTP failures, and reproduce the fix with small examples.
Read the worked guide
Practical utilities for everyday development
Free Online Developer Tools built for real debugging work
Format and compare JSON, inspect URLs, test regular expressions, review AI-generated code, and convert development data without creating an account.
✓ Free to use
✓ No registration
✓ Clear processing notices
New: Daily Developer Debug
Can you spot today’s bug?
One practical challenge, a clear explanation, local streaks, and shareable results.
Start working
Focused tools for common tasks
A smaller selection of useful workflows. Browse the complete collection when you need something more specific.
A
AI Developer Tools
AI Code Change Inspector
Compare original and AI-generated JavaScript, PHP or Laravel code, inspect review signals and build a focused regression test plan locally.
J
JSON Tools
JSON Formatter
Format, beautify, validate, sort and minify JSON instantly for API debugging and development.
J
JSON Tools
JSON Validator
Validate JSON data online and find syntax issues before they break your API or application.
J
JSON Tools
JSON Diff Checker
Compare two JSON documents by structure and inspect changed, added and removed values with JSON Pointer paths.
C
JSON Tools
CSV to JSON Converter
Convert comma-separated records into JSON objects while preserving quoted commas, multiline cells and leading zeros.
U
API Tools
URL Parser & Query Inspector
Inspect URL components and repeated query parameters using the browser URL parser, with an optional base for relative paths.
AI-assisted development
Review generated code before you trust it.
Compare an original file with an AI revision, identify changes worth investigating, and turn those findings into focused regression checks.
01
Compare behavior
Read additions and removals in the context of the behavior the application must preserve.
02
Review risk signals
Investigate validation, authorization, network, logging, dependency, and execution changes.
03
Prepare tests
Turn acceptance criteria and review findings into concrete regression cases.
04
Keep human judgment
Pattern signals guide review; they do not prove that generated code is safe or correct.
Worked examples
Learn the workflow, not just the button
Task-focused guides explain the example, the expected result, important edge cases, and where a lightweight browser tool stops being enough.
API authentication
JWT decoding vs verification: debug a token safely
Understand the difference between reading JWT claims and verifying a signature, with a practical checklist for API authentication failures.
Read the worked guideData conversion
Convert JSON to CSV without silently losing fields
Handle inconsistent JSON fields, commas, quotes, nested values and spreadsheet formulas when exporting API records as CSV.
Read the worked guideAI development
Write AI coding prompts you can verify
Give an AI assistant a reproducible coding task, concrete constraints and acceptance criteria, then evaluate its answer with meaningful tests.
Read the worked guideTransparent by design
Know how a tool handles your input.
DevToolPlace uses both browser-side and server-side processing. Each tool displays the relevant processing notice so you can choose appropriate test data.
Read the privacy policy →Browser tools
Selected utilities run in the browser and do not send their working input to a tool-processing endpoint.
Server tools
Some Livewire utilities send input to the application server for processing. Avoid active secrets and private production data.
No account required
Core tools are available without registration, profiles, or a saved workspace.
Limits are documented
Tool pages explain important input limits, caveats, and cases where a dedicated library is more appropriate.
Common questions
Using DevToolPlace responsibly
Are the tools free?
Yes. The public developer utilities can be used without creating an account.
Should I paste production credentials?
No. Use redacted examples and test values. Avoid active API keys, passwords, access tokens, customer records, and confidential source code in any online tool.
Does a formatter validate business rules?
Usually not. Formatting confirms structure and readability; application schemas, authorization rules, and domain validation still belong in your project and test suite.
How can I report an incorrect result?
Use the contact page and include the tool URL, a small redacted example, the expected result, and the actual result.