Free online developer tools
Find a focused tool for reading data, debugging connections or preparing test files. Examples explain input and output; verify data and environment before production use.
Data, code and identifiers
JSON syntax validation checks structure; use JSON Schema for field rules. Formatting, structural comparison, regex testing and UUID generation solve different tasks.
JSON formatter & validator
Format, minify and validate JSON; check JSONL records and convert JSONL and JSON arrays.
JSON Schema validator
Validate JSON with JSON Schema Draft 2020-12.
JSONPath evaluator
Run property, array-index and wildcard JSONPath queries against JSON.
JSON key renamer
Recursively change JSON key casing or add a custom prefix and suffix.
JSON diff checker
Compare JSON structure and values, optionally ignoring array order or named fields.
JSON merger
Deep-merge two JSON objects and concatenate their arrays.
JSON to Go struct
Infer JSON field types and generate a tagged Go struct.
JSON to Java class
Infer JSON field types and generate a Java data class.
UUID / GUID generator
Generate UUID/GUID v1, v3, v4, v5 or v7 in batches. Choose letter case, remove hyphens for 32-character IDs, and copy individual values or all results.
ULID generator
Generate time-sortable 26-character ULIDs in bulk and inspect their timestamp.
JavaScript formatter
Format or minify JavaScript with configurable indentation.
SQL formatter & minifier
Format common SQL keywords and clauses or remove extra whitespace.
XML formatter & validator
Validate XML syntax and format it with readable indentation.
Regular expression tester
Test JavaScript regex patterns, flags, positions and capture groups.
Common regex reference
Search regular expressions for common formats such as email, URL, IPv4, dates, UUIDs, colors and ports.
Requests, serialization and databases
Inspect request code, WebSocket messages and binary data, or generate database structures and connection strings. Network tests connect to the address you enter; use only services you may access.
WebSocket tester
Connect to WS or WSS servers, view live server messages, and send plain text or JSON messages to debug/test WebSocket services.
cURL to code
Convert a cURL request to JavaScript, Python, Go or Java code.
Protocol Buffers codec
Encode or decode Protocol Buffers data using a .proto definition.
MessagePack and JSON
Convert JSON to MessagePack Base64 or decode it back to JSON.
Binary structure parser
Parse hexadecimal bytes as integers or floating-point values with a chosen byte order.
Database creation SQL generator
Generate database, user and permission setup SQL for common databases.
Database table SQL generator
Configure columns, types and constraints to generate CREATE TABLE SQL instantly.
Database connection string builder
Build properly encoded PostgreSQL, MySQL, MongoDB and Redis URLs.
Test data and development resources
Prepare inputs with mock data and CSV, look up Git commands or work on fonts and badges. Review generated code and commands before running them in a real project.
Fake data generator
Define nested JSON structures and typed generation rules, then export test records as JSON, JSONL or CSV.
CSV data processor
Import or paste CSV, detect delimiters, filter rows, select columns, sort, deduplicate and trim whitespace. Preview and export CSV or JSON.
Git command reference
Search common Git configuration, branch, commit, remote, undo and stash commands by category.
Font file preview
Open a TTF, OTF, WOFF or WOFF2 font and preview custom text.
Font subsetter
Create a downloadable TTF font subset containing selected characters.
Shield badge maker
Create a Shield-style SVG badge for a README or documentation.
Keyboard key information
Inspect key, code, keyCode, modifiers and repeat state from keyboard events in real time.