Free Online Developer Tools

Base64 Encoder / Decoder

Encode text to Base64 or decode Base64 back to text. UTF-8 safe, handles any language.

JWT Decoder

Paste a JSON Web Token to inspect its header, payload claims, and expiry — no secrets leave your browser.

CIDR / Subnet Calculator

Calculate network address, broadcast, usable host range, and netmask from any IPv4/CIDR.

Subnet Calculator

Enter an IP plus a dotted mask or /prefix to get the network, broadcast, and host range.

Unix Timestamp Converter

Turn epoch seconds/ms into UTC and local time, or a date into a Unix timestamp.

URL Encoder / Decoder

Percent-encode text for URLs or decode URL-encoded strings. UTF-8 aware.

Cron Expression Explainer

Type a 5-field cron or use a preset to get a plain-English schedule explanation.

YAML to JSON

Paste YAML and get formatted JSON. Handles nested maps, lists, and scalars.

JWT Generator

Build HS256 (or unsigned) JSON Web Tokens from a JSON payload and a secret.

Regex Tester

Test JavaScript regex against any text, see every match, group, and position.

Text to Hex

Encode text to space-separated UTF-8 hex bytes.

Hex to Text

Decode hex bytes back into UTF-8 text.

Text to Binary

Convert text into 8-bit binary groups.

Binary to Text

Decode binary bits back to text.

HTML Entity Encoder

Escape text into HTML-safe entities.

HTML Entity Decoder

Decode named and numeric entities.

UTF-8 Encode / Decode

Inspect UTF-8 byte values.

Slugify

Turn titles into clean URL slugs.

Nonce Generator

Cryptographic random nonces.

API Key Generator

Random URL-safe API keys.

Token Generator

Secure random tokens.

Number Formatter

Add thousands separators to numbers.

Line Sorter & Dedupe

Sort lines, drop duplicates.

Find & Replace

Swap exact text.

Whitespace Remover

Collapse or strip whitespace.

IP to Decimal

IPv4 to a 32-bit integer.

Decimal to IP

Integer back to IPv4.

IP Range to CIDR

Minimal CIDR covering set.

Hash Generator

SHA-1 / SHA-256 / SHA-384 / SHA-512 checksums, computed locally.

HMAC Generator

Keyed HMAC-SHA signatures for API auth and webhook verification.

UUID Generator

Generate v4 UUIDs in bulk using the browser CSPRNG.

CSV to JSON

Convert CSV rows to JSON objects, quoted fields handled.

JSON to CSV

Flatten a JSON array into a CSV table with a header row.

XML to JSON

Parse XML into JSON, including attributes and repeated tags.

JSON to XML

Serialise JSON to indented, escaped XML.

JSON / YAML Validator

Validate and pretty-print JSON, lint YAML structure.

SQL Formatter

Uppercase keywords and break long queries onto readable lines.

CSS Minifier

Strip comments and whitespace from stylesheets.

JS Minifier

Basic JavaScript minification that leaves string literals alone.

Diff Checker

Line-by-line comparison of two texts with added and removed marks.

Epoch to Date

Convert Unix timestamps to readable dates and back.

Timezone Converter

Move a time between timezones using the browser's IANA database.

Hex / RGB Converter

Convert colours between hex and RGB in both directions.

Word / Character Counter

Count words, characters, lines, and sentences.

Case Converter

Switch text between lower, upper, title, camel, snake, and kebab case.

Punycode Converter

Convert internationalised domain names to and from xn-- form.

Image to Base64

Turn a local image into a data URI without uploading it.