Browser utilities
Developer Tools
All tools are free. No account, subscription or API key required.
Merge PDF, split PDF, format JSON, encode Base64, generate UUIDs — each tool has its own page for search and sharing.
JSON Formatter
Pretty print and validate JSON
Base64 Encoder
Encode and decode Base64 strings
UUID Generator
Create unique IDs instantly
SQL Formatter
Clean up messy SQL queries
Regex Tester
Test patterns against sample text
Hash Generator
MD5, SHA-1, SHA-256 hashes
URL Encoder
Encode and decode URL strings
JWT Decoder
Inspect JWT header and payload
Timestamp Converter
Unix time ↔ human date
Markdown Preview
Write markdown, see HTML preview
JSON to Code Generator
Generate TypeScript types, JSON Schema and Laravel validation rules.
Text & JSON Diff Checker
Compare text or inspect changes between JSON documents.
Mock Data Generator
Create sample users, products and orders as JSON, CSV or SQL.
cURL to Code Converter
Convert a cURL request to Fetch, Python or Laravel code.
Cron Builder & Explainer
Build a schedule and preview upcoming runs in your timezone.
Merge PDF
Combine PDF files in your chosen order.
Online Compiler
Write and run JavaScript, Python, HTML and CSS in our Online Compiler.
Open compiler →Tool questions
Are Codementrix developer tools free?
Yes. Every public tool is free and does not require an account or API key.
Can I merge PDF files online here?
Yes. Open the Merge PDF tool, add files in order, and download the combined PDF. Processing stays in your browser.
Do files upload to a server?
PDF and formatter tools run in your browser. We do not ask you to create an account to use them.