Developer tool categories

Explore 75+ free online developer tools by category. JSON formatters, Base64 encoders, JWT decoders, Unix timestamp converters, cron parsers, and more — all private and client-side.

View all JSON tools →

JSON

15 tools

Format, validate, explore, and transform JSON data.

JSON Formatter

Beautify, minify, and validate JSON instantly in your browser.

JSON Viewer

Explore JSON as an interactive tree with search and expand controls.

JSON Validator

Validate JSON syntax instantly with clear error messages.

JSON Minifier

Minify JSON into a compact single-line payload.

JSON Prettifier

Pretty-print JSON with clean indentation for readability.

JSON Compare

Compare two JSON documents and highlight structural changes.

JSON Diff

Generate a line-by-line diff of two JSON documents.

JSON to YAML

Convert JSON into clean YAML instantly.

JSON to XML

Convert JSON data into XML markup.

JSON to CSV

Flatten JSON into CSV for spreadsheets and exports.

JSON to TypeScript

Generate TypeScript interfaces from JSON samples.

JSON to Java

Generate Java class stubs from JSON data.

JSON to C#

Generate C# classes from JSON samples.

JSON to PHP Array

Convert JSON into a PHP array literal.

Escape / Unescape JSON

Escape text into JSON strings or unescape JSON literals.

View all Encoding & Decoding tools →

Encoding & Decoding

49 tools

Encode and decode Base64, URL, HTML, Unicode, JWT, binary, and more — entirely in your browser.

Base64

Base64 Encoder

Encode text to Base64 instantly in your browser.

Base64 Decoder

Decode Base64 strings back to readable text.

Base64 Image Decoder

Preview images from Base64 or Data URI strings.

Base64 Image Encoder

Convert images to Base64 for embedding in CSS or HTML.

Base64 URL Encoder

Encode text as URL-safe Base64 (Base64URL).

Base64 URL Decoder

Decode URL-safe Base64 (Base64URL) strings.

URL

URL Encoder

Percent-encode text for safe use in URLs.

URL Decoder

Decode percent-encoded URL strings.

URL Parser

Break a URL into protocol, host, path, query, and hash.

URL Query Parser

Parse query strings into a readable JSON object.

URL Builder

Build a full URL from JSON parts.

URL Query String Generator

Turn a JSON object into a query string.

HTML

HTML Encoder

Encode special characters for safe HTML output.

HTML Decoder

Decode HTML entities back to plain text.

HTML Escape

Escape HTML to prevent XSS in text contexts.

HTML Unescape

Unescape HTML entities to original characters.

Unicode

Unicode Encoder

Convert text to Unicode escape sequences.

Unicode Decoder

Decode \uXXXX and \u{…} escape sequences.

Unicode Escape

Escape text as Unicode code-point sequences.

Unicode Unescape

Unescape Unicode sequences to readable text.

ASCII ↔ Unicode Converter

Convert between plain text and Unicode escapes.

JWT

JWT Decoder

Decode JWT header and payload without a server.

JWT Generator

Generate HS256 JWTs locally with Web Crypto.

JWT Inspector

Inspect JWT claims in a readable JSON view.

JWT Expiry Checker

Check iat, nbf, and exp claims on a JWT.

Text Encoding

UTF-8 Encoder

Encode text to UTF-8 byte values.

UTF-8 Decoder

Decode UTF-8 byte lists back to text.

UTF-16 Converter

Convert text to and from UTF-16 code units.

ASCII Converter

Convert text to ASCII / Unicode code points.

Binary Converter

Convert text to binary and back.

Hex Converter

Convert text to hexadecimal and back.

Octal Converter

Convert text to octal byte values and back.

Binary & Hex

Text → Binary

Convert plain text into binary bytes.

Binary → Text

Convert binary bytes back into text.

Text → Hex

Convert plain text into hexadecimal.

Hex → Text

Convert hexadecimal into text.

Binary ↔ Hex

Convert between binary and hexadecimal.

Decimal ↔ Binary

Convert decimal numbers to binary and back.

Decimal ↔ Hex

Convert decimal numbers to hex and back.

Data URI

Data URI Generator

Build data: URIs from MIME type and content.

Data URI Decoder

Decode data: URIs back to MIME + payload.

Image → Data URI

Upload an image and get a ready-to-use Data URI.

MIME

MIME Type Lookup

Look up MIME types from file extensions.

MIME Header Decoder

Decode RFC 2047 encoded-word email headers.

MIME Header Encoder

Encode text as RFC 2047 UTF-8 Base64 headers.

QR & Barcode

QR Code Generator

Generate QR codes from text or URLs locally.

QR Code Decoder

Decode QR codes from uploaded images.

Barcode Generator

Generate CODE128, EAN13, UPC, and more barcodes.

Barcode Reader

Capture or paste barcode values for quick notes.

View all Date & Time tools →

Date & Time

5 tools

Convert timestamps, compare dates, shift time zones and work with cron expressions.

Unix Timestamp Converter

Convert Unix timestamps to human-readable dates and back.

Date Difference Calculator

Calculate the exact difference between two dates.

Time Zone Converter

Convert a date and time between world time zones.

Cron Expression Parser

Explain cron schedules and preview upcoming run times.

Cron Expression Generator

Build and validate 5-field cron expressions visually.

View all OpenAPI tools →

OpenAPI

6 tools

View, validate, format, convert, and diff OpenAPI / Swagger specs — entirely in your browser.

OpenAPI

OpenAPI Viewer

Explore OpenAPI / Swagger specs — paths, operations, schemas, and security.

OpenAPI Validator

Validate OpenAPI 2.0, 3.0, and 3.1 documents with clear errors and warnings.

OpenAPI Formatter

Pretty-print or minify OpenAPI JSON and YAML with indent and key sorting.

JSON to OpenAPI

Infer schemas from sample JSON and generate an OpenAPI 3.1 document.

OpenAPI Example Generator

Generate realistic request and response examples from an OpenAPI spec.

OpenAPI Diff

Compare two OpenAPI specs for added, removed, and breaking changes.