Developer Tools

JSON, Base64, JWT, hashes, regex, cron and other coding utilities.

A fast, no-nonsense toolbox for developers, testers and data folks. Format and validate JSON, encode and decode Base64 or URLs, generate UUIDs and hashes, decode JWTs, test regular expressions and translate cron expressions — all without installing anything.

Your code and data stay in your browser: nothing is sent to a server, which makes MaxTools safe for sensitive work such as tokens, keys and personal payloads.

All developer tools

JSON Formatter & Validator

Format, minify and validate JSON instantly with clear error messages that point at the exact problem.

JSON Validator

Check if your JSON is valid and find syntax errors with exact line and column.

JSON Minifier

Compress JSON to its smallest valid form for storage and transport.

JSON to CSV

Convert a JSON array of objects into a clean CSV file in one click.

CSV to JSON

Convert CSV (from Excel or Google Sheets) into a JSON array of objects.

Base64 Encoder

Encode text or files to Base64 — standard or URL-safe — in your browser.

Base64 Decoder

Decode Base64 back to readable text — UTF-8 safe, instant and private.

URL Encoder

Percent-encode text for URLs and query strings instantly.

URL Decoder

Decode percent-encoded URLs and query values back to readable text.

URL Parser

Break any URL into protocol, host, path, query parameters and hash.

UUID Generator

Generate multiple UUIDv4 identifiers instantly — uppercase or hyphen-free.

UUID Validator

Validate UUID format and identify its version and variant instantly.

MD5 Generator

Compute the MD5 hash of any text instantly for checksums and legacy systems.

SHA256 Generator

Compute the SHA-256 hash of any text — the modern integrity standard.

Hash Generator

Generate MD5, SHA-1, SHA-256 or SHA-512 hashes from one input.

JWT Decoder

Decode JWT header, payload and claims — with readable expiry timestamps.

JWT Generator

Create a signed HS256 JWT from your own payload and secret — locally.

Color Converter

Convert colors between HEX, RGB, HSL and CMYK with a live preview.

Regex Tester

Test regular expressions live with matches, positions and capture groups.

Cron Expression Generator

Build standard 5-field cron expressions with human-readable explanations.

QR Code Generator

Create scannable QR codes from URLs, text or Wi-Fi configs — download PNG.

Barcode Generator

Generate EAN-13 retail barcodes — check digit computed automatically.

HTML Encoder

Escape text for safe HTML — encode &, <, >, quotes and non-ASCII.

HTML Decoder

Convert HTML entities back to readable text — named and numeric.

Slug Generator

Turn any title into a URL-friendly slug — lowercase, hyphenated, trimmed.

Markdown to HTML Converter

Convert Markdown to HTML with live preview — headings, tables, code.

YAML Converter

Convert between YAML and JSON in both directions.

CSV Viewer

Preview CSV files as a clean table — no spreadsheet needed.

HTTP Status Codes

Every HTTP status code explained — searchable reference for debugging.

MIME Type Lookup

Find the MIME type for any file extension — and vice versa.

Credit Card Validator

Validate card numbers with the Luhn checksum and detect the brand.

IBAN Validator

Validate international bank account numbers — structure and mod-97 checksum.

Color Contrast Checker

Check WCAG contrast ratios for text and background color pairs.

Color Picker from Image

Extract colors from any image — hover to sample, click to collect.

Password Strength Checker

Analyze password strength: entropy, character classes and crack-time estimates.

.gitignore Generator

Build .gitignore files from templates for Node, Python, Java, Go and more.

chmod Calculator

Convert Unix permissions between symbolic and numeric modes.

IP Subnet Calculator

Calculate network, broadcast, mask and usable hosts from any IPv4 CIDR.

ASCII Table

Decimal, hex, octal and binary for every ASCII character — searchable.

HTML CSS JS Preview

Live HTML/CSS/JS playground in a sandboxed iframe — edit and run.

Looking for something else? Browse the other free tool collections: Financial Calculators · Date & Time Tools · Unit Converters · Text Tools · File & Image Tools · Health & Fitness Calculators · Everyday Tools · Fun & Generators · Math & Statistics.