Developer Tools

Format, minify, encode and generate.

67 free tools — no signup, runs in your browser

AES Encrypt and Decrypt

AES-256-GCM encryption with a passphrase.

ASCII and Unicode Table

The ASCII table, plus details for any character you paste.

Base32 and Base58 Converter

Encode and decode Base32 and Base58.

Base64 Decoder

Decode Base64 back to text.

Base64 Encoder

Encode text to Base64.

Box Shadow Generator

Build a CSS box-shadow with live values.

Byte Size Converter

Convert between KB, MB, GB, TB and their KiB counterparts.

CRC32 Checksum Calculator

CRC32 and Adler-32 checksums for text or a file.

CSS Beautifier

Re-indent minified CSS into something readable.

CSS Gradient Generator

Build linear, radial and conic CSS gradients.

CSS Minifier

Minify CSS by stripping comments and whitespace.

CSS Unit Converter

Convert between px, rem, em, %, pt and physical units.

CSS Validator

Catch unbalanced braces and broken declarations.

Color Converter

Convert a colour between HEX, RGB, HSL, HSV and CMYK.

Connection String Builder

Build a database URL with the password escaped correctly.

Contrast Checker

Check colour contrast against the WCAG thresholds.

Credit Card Validator

Check a card number's Luhn checksum and identify the issuer.

Cron Expression Tool

Explain a cron expression and list its next runs.

Cubic Bezier Generator

Build CSS easing curves, or start from a preset.

Escape and Unescape String

Escape text for JavaScript, JSON, SQL, HTML, shell and more.

File Hash Checker

Hash a file and compare it against a published checksum.

Flexbox and Grid Generator

Generate CSS Flexbox or Grid layout rules.

GZIP Compressor

Compress or expand text with GZIP or Deflate.

HMAC Generator

Sign a message with a secret key using HMAC.

HTML Entity Reference

Every common HTML entity with its character and code.

HTML Formatter

Pretty-print and indent HTML.

HTML Minifier

Shrink HTML without breaking pre or textarea content.

HTML Validator

Find unclosed tags, bad nesting and missing alt text.

HTTP Status Code Reference

Every HTTP status code, with notes on when to use it.

Hash Generator

MD5, SHA-1, SHA-256, SHA-512 and more, from any text.

IEEE 754 Float Converter

See the exact bits behind a floating-point number.

JS Minifier

Basic JavaScript minifier (removes comments and extra whitespace).

JSON Diff

Compare two JSON documents by value, not by text.

JSON Formatter

Pretty-print and indent JSON.

JSON Minifier

Minify JSON by removing whitespace.

JSON Validator

Validate JSON and report syntax errors.

JSON Viewer

Flatten JSON into one searchable path per value.

JSON to CSV Converter

Convert JSON to CSV or TSV, and CSV back to JSON.

JSON to TypeScript Types

Turn a JSON sample into TypeScript, Python or Go models.

JSON to XML Converter

Convert JSON to XML and XML back to JSON.

JSON to YAML Converter

Convert JSON to YAML and YAML back to JSON.

JSONPath Tester

Query JSON with a dotted path and see what it returns.

JWT Decoder

Read a JWT's header, payload and expiry.

JWT Encoder

Sign a JSON payload into a JWT with HMAC.

JavaScript Beautifier

Re-indent minified JavaScript or TypeScript.

JavaScript Obfuscator

Hide string literals and strip comments from JavaScript.

JavaScript Syntax Checker

Check brackets, quotes and comments before you debug.

MIME Type Lookup

Find the MIME type for any file extension.

Markdown Table Generator

Turn CSV or TSV rows into an aligned Markdown table.

Mock SQL Generator

Generate CREATE TABLE and INSERT statements from a JSON sample.

Password Generator

Generate strong random passwords.

README Generator

Generate a project README with the usual sections.

Regex Cheat Sheet

Every regex token explained, with ready-made patterns.

Regex Tester

Test a regular expression and see every match and group.

Responsive srcset Generator

Build a responsive img tag with srcset and sizes.

SQL Formatter

Break a long SQL statement onto readable lines.

SQL Minifier

Strip comments and whitespace from an SQL statement.

SVG Optimizer

Strip the editor metadata that bloats an exported SVG.

Subnet Calculator

CIDR maths for IPv4 and IPv6 networks.

TOML and INI Converter

Convert between TOML, INI and JSON.

UUID Generator

Generate one or more random UUID v4 values.

Unix Timestamp Converter

Convert Unix timestamps to dates and back.

User Agent Parser

Read the browser, OS and device out of a User-Agent string.

XML Formatter

Pretty-print or minify XML, and catch syntax errors.

cURL to Code Converter

Turn a cURL command into JavaScript, Python, Go or PHP.

gitignore Generator

Build a .gitignore for the stacks you actually use.

htpasswd Generator

Generate an Apache or nginx .htpasswd line.

ToolSimpli's developer tools are built to speed up everyday coding tasks without switching between multiple apps or installing extensions. Use the JSON formatter to instantly beautify messy JSON, or the JSON validator to catch syntax errors before they break your application, and the JSON minifier when you need to shrink JSON payloads for production.

Encoding and decoding data is a routine part of development. Our Base64 encoder converts text and files to Base64 in one click, the Base64 decoder reverses the process, and the dedicated Base64 to image converter and image to Base64 converter make it easy to embed images directly in code or extract images from encoded strings.

Shipping faster, lighter code matters for performance. The CSS minifier and JS minifier strip out unnecessary whitespace and comments to shrink file sizes and improve page load times, while the HTML formatter cleans up and indents markup for easier reading and debugging. For generating unique identifiers in databases and APIs, the UUID generator produces valid, random UUIDs instantly.

All developer tools on ToolSimpli run client-side friendly workflows in the browser, require no account, and support copy-paste or file upload where relevant. Whether you're debugging an API response, preparing assets for production, or generating test data, this toolkit is designed to be fast, accurate and free to use as often as you need. Browse the full list below to find the right developer tool for your workflow.