90 free tools · no sign-up · zero ads · 100% local, baby

FlowingDev — One place, every tool for devs.

One place, every tool for devs.

Format, validate, inspect and transform JSON, XML, YAML, JWTs, Markdown and more. So private your data never leaves your browser: zero server round-trips, zero tracking of what you paste, and zero ads.

100% browser-sideYour data never leavesZero adsNo login, no friction

Auto-detect any format

The Toolbox

Pick your weapon

Viewers

JSON Viewer

Pretty-print, validate and squish JSON. No server involved.

XML Viewer

Tame ugly XML and poke around its tree structure.

JWT Viewer

Crack open a JWT and peek at its header, payload and expiry.

YAML Viewer

Check your YAML's indentation sins and flip it to/from JSON.

Markdown Viewer

Type Markdown, watch it render live — zero XSS surprises.

SQL Viewer

Untangle messy SQL into something your eyes can parse.

HTTP Message Viewer

Paste raw HTTP and get a readable, field-by-field breakdown.

HTML Viewer

Drop in HTML and watch it render right beside the source.

CSS Viewer

Explore a stylesheet as a tree with color swatches, specificity, stats and one-click copy.

.NET Assembly Inspector

Open a .NET DLL or EXE to browse its metadata, types, members and IL, and decompile it back to C#, in your browser.

Protobuf Decoder

Decode raw Protocol Buffers messages from hex, Base64 or a file without a .proto schema: fields, wire types, nested messages and JSON.

Converters & encoders

Base64 Tools

Base64 in, Base64 out, with a live preview — no guesswork.

URL Encoder

URL-encode or decode whole links or just the fiddly bits.

Hash Generator

Crank out MD5 and SHA hashes without pinging a server.

CSV Tools

Turn messy CSV into a table, or flip it to and from JSON.

Cron Expression Parser

Decode cron syntax into plain English and the next run times.

Epoch Converter

Flip Unix timestamps to dates and back, plus a live clock.

CSS Unit Converter

Convert px, rem, em, vw and friends, and build fluid clamp() values.

Unit Converter

Convert length, temperature, volume, weight, speed, acceleration, pressure, energy, data and more.

Base Converter

Type a number in binary, octal, decimal, hex or any base 2–36 and see all the others update live.

Base Calculator

Programmer and scientific calculator that thinks in binary, hex, octal or any base 2–36, with bitwise ops and a clickable bit view.

Text Encoding Detector

Find out which encoding a text file uses (UTF-8, UTF-16, Latin-1, Shift_JIS…) and convert it to any other, BOM and line endings included.

Case Converter & Slugify

Convert identifiers between camelCase, snake_case, kebab-case, PascalCase, CONSTANT_CASE and more, plus clean URL slugs.

JSON to Code

Turn a JSON sample into typed models (TypeScript, Zod, C#, Python, Go, Java, Kotlin, PHP, Rust) and ready-to-run HTTP client code (HttpClient, RestSharp, fetch, Axios, requests, OkHttp, Guzzle…).

Docker Run to Compose

Convert docker run commands into a docker-compose.yml and back: ports, volumes, env, healthchecks, limits and more.

Validators & testers

Regex Tester

Throw your regex at real text and see what matches (and what doesn't).

Diff Checker

Diff two files side by side and see exactly what changed.

Merge Tool

Merge two file versions side by side — pick a side per change, done.

Unicode Text Inspector

X-ray any string: reveal zero-width and invisible characters, odd spaces and look-alike letters, then clean them up.

Network & APIs

cURL to Code

Turn a cURL command into fetch, Axios, Python, Go or PHP code.

HTTP Message Builder

Build raw HTTP requests or responses, headers, body and files included.

Subnet / CIDR Calculator

Crunch an IPv4 CIDR into network, broadcast, hosts and masks.

GraphQL Formatter

Make GraphQL queries and schemas readable (or squish them down).

HAR Viewer

Open a DevTools HAR export and explore every request with a waterfall, timings, headers, bodies and filters.

SVG & images

SVG Optimizer

Clean, shrink and preview SVGs, then export as Data URI or Base64.

Favicon Generator

Turn one image into every favicon size plus the head tags.

Image ↔ Base64

Flip images to Base64/Data URI and back, with resize and compression.

Image Converter

Convert JPG/PNG/GIF to WebP (or back), resize, compress, download.

WebP Converter

Convert JPG, PNG or GIF images to WebP in one step, with quality and resize controls, and see how many KB you save.

SVG to JSX

Convert SVG markup into a clean React component (JSX or TSX) with props, currentColor, forwardRef and camelCased attributes.

Security

Encryption Tools

Lock and unlock text with password-based AES encryption.

CSP Checker

Scan your CSP header for sketchy directives and gaps.

Security Headers

Get a report card on your security headers, plus fixes.

Password Strength

See how fast a password would crack, patterns and all.

SRI Hash Generator

Generate SRI hashes and the script/link tags that use them.

HMAC Generator

Sign payloads with HMAC and double-check webhook signatures.

Chmod Calculator

Translate Unix permissions between octal, symbolic and checkboxes, with SUID/SGID/sticky bits, umask and ready-to-copy commands.

Certificate Viewer

Decode PEM X.509 certificates, chains and CSRs: subject, issuer, expiry, SANs, extensions and fingerprints.

Certificate & Keys

Generate CSRs, create and open PKCS#12 (PFX) bundles, and convert keys and certificates between PEM, DER, PKCS#1 and PKCS#8 — all locally.

SSH Key Generator

Generate Ed25519, ECDSA or RSA SSH key pairs in OpenSSH format and compute key fingerprints, with the private key never leaving your browser.

TOTP / 2FA Generator

Generate and verify TOTP 2FA codes from a Base32 secret, build otpauth:// URIs and QR codes for authenticator apps.

Bcrypt & Argon2 Hash

Hash passwords with bcrypt or Argon2id, tune the cost and verify a password against an existing hash.

Editors

JS / TS Tools

Tidy up or shrink your JS/TS — your pick, your style.

JavaScript Obfuscator

Sends your JS through the obfuscation grinder: renamed identifiers, encoded strings, flattened control flow and more — all on your device.

Code Indenter

Fix busted indentation across JS, TS, JSON, HTML, CSS, YAML and more.

JSON Editor

Edit JSON as text, tree, table or form — side by side, then download.

XML Editor

Edit XML as text, tree, table or form — side by side, then download.

YAML Editor

Edit YAML as text, tree, table or form — side by side, then download.

Markdown Editor

Write Markdown and rich text side by side — toolbar included, always in sync.

HTML Editor

Edit HTML with a live preview, auto-formatting and a one-click download.

CSS Editor

Edit CSS as text or as an editable tree, with a live preview on your own HTML.

Playgrounds

HTML/CSS/JS Playground

Write HTML, CSS and JavaScript and see the result live, with a built-in console.

TypeScript Playground

Run TypeScript instantly in your browser: types are stripped on the fly and output shows in the console.

React Playground

Write React components with JSX/TSX and hooks and see them render live.

Angular Playground

Try Angular standalone components, signals and templates live in your browser.

SQL Playground

Run SQL against a real SQLite database inside your browser and see results as tables.

Python Playground

Run real Python 3 (CPython on WebAssembly) in your browser, with packages like numpy.

PHP Playground

Run PHP scripts in your browser with a real PHP interpreter compiled to WebAssembly.

Ruby Playground

Run Ruby code in your browser with CRuby compiled to WebAssembly.

Lua Playground

Run Lua 5.4 scripts instantly in your browser.

C# Playground

Compile and run C# with the real Roslyn compiler and .NET runtime in your browser, then export the DLL.

Generators

UUID Generator

Spit out one or a thousand UUIDs, formatted your way.

Random Generator

Generate random numbers or strings with your own charset.

Lorem Ipsum Generator

Fill the void with as much Lorem Ipsum as you need.

Password Generator

Cook up strong passwords with length and charset to taste.

QR Code Generator

Make QR codes from any text or link, with color and size options.

Barcode Generator

Generate Code 128, EAN-13, UPC and more barcodes, ready to download.

Mock Data Generator

Spin up realistic fake JSON records for your tests, field by field.

Colors

Color Picker & Converter

Pick a color and juggle it between HEX, RGB, HSL, OKLCH and more.

Web Palette Generator

Turn one brand color into a full site palette, then preview it live.

Contrast Checker

Check WCAG contrast and get an instant fix if it fails.

Random Color Generator

Spin up random colors that actually look distinct from each other.

Color Scale Generator

Build a Tailwind-style 50-950 scale from any color, export-ready.

Box Shadow Generator

Design smooth multi-layer CSS box-shadows with a live preview and copy them as CSS or Tailwind.