Free developer tools

Online developer tools are small, single-purpose utilities for the everyday chores of writing software: formatting and validating JSON, SQL, and XML, decoding JWTs, testing regular expressions, explaining cron schedules, calculating chmod permissions and CIDR ranges, and generating hashes, UUIDs, and mock data. Every formatter, decoder, tester, and calculator here runs inside your browser, so your code and tokens never leave your device. The AI-assisted generators send only the text you type. Nothing to install, no account needed, and the core tools are free without limits.

35 tools · free · no sign-up

HTTP Status Codes

Look up any HTTP status code and what it means.

User Agent Parser

See and decode any browser user-agent string.

Mock Data Generator

Generate fake test data as JSON or CSV.

ASCII Table

Full ASCII table — decimal, hex, binary, and characters.

.gitignore Generator

Build a .gitignore for your languages and tools.

CSV to JSON

Convert CSV to JSON in your browser.

URL Parser

Break a URL into its parts and query params.

AI Regex GeneratorPro

Turn plain English into a regular expression.

AI SQL GeneratorPro

Write SQL queries from plain English.

AI Code ExplainerPro

Understand what any code does, in plain English.

AI Commit Message GeneratorPro

Generate clear commit messages from a diff.

AI Cron Expression GeneratorPro

Turn a schedule in plain English into cron.

JSON Formatter

Format, validate, and minify JSON — instantly, in your browser.

SQL Formatter

Beautify and format SQL queries for any dialect.

XML Formatter

Beautify, indent, and validate XML.

Code Beautifier

Format JavaScript, CSS, HTML, and JSON.

Markdown Editor

Write Markdown with a live preview — copy the HTML instantly.

JSON to TypeScript

Generate TypeScript types from JSON.

JSON to JSON Schema

Generate a JSON Schema from an example JSON object.

cURL to Code

Convert a cURL command to JavaScript fetch or Python requests.

PX to REM Converter

Convert between px, rem, and em for CSS.

JWT Decoder

Decode and inspect JSON Web Token header and payload.

Regex Tester

Test regular expressions against sample text with live matches.

Cron Expression Explainer

Translate a cron expression into plain English.

Color Contrast Checker

Check WCAG contrast between two colors.

Chmod Calculator

Convert file permissions between octal and symbolic.

CIDR / Subnet Calculator

Calculate subnet range, mask, and host counts from CIDR.

What Is My IP Address

See your public IP address and browser details instantly.

Credit Card Validator (Luhn)

Check a card number's Luhn checksum and detect its brand.

Password Strength Checker

Test how strong a password is, privately.

Bcrypt Generator

Generate and verify bcrypt password hashes — Laravel & PHP compatible.

SVG Optimizer

Minify and clean up SVG code to shrink the file.

HTML Minifier

Minify HTML — strip comments and whitespace.

CSS Minifier

Minify CSS to shrink stylesheet size.

JavaScript Minifier

Minify JavaScript with Terser.

Which of these developer tools send your data anywhere?

Most tools on this page never send your data anywhere. The formatters, validators, decoders, converters, testers, and calculators all run as JavaScript inside the tab you already have open, so your code, tokens, and configuration files stay on your machine and the tools keep working if your connection drops. That matters because developer utilities routinely handle production secrets: a JWT from a live session, an API response with customer records, a connection string in a config file. Pasting those into a site that processes them on a server means handing them to a third party. The exception here is the AI-assisted generators, such as the regex and SQL helpers, which necessarily send the text you type to an AI provider to produce a result; those are labelled and need an account. Nothing you enter is stored by OhoTool either way, and no tool on this page requires sign-up.

Frequently asked questions

Do these tools send my data anywhere?

The formatters, decoders, testers, and calculators run entirely in your browser and send nothing. The AI-assisted generators necessarily send the text you type to an AI provider to produce a result; those tools are labelled and need a free account. OhoTool does not store your input or output either way.

Is the JWT decoder safe to use?

Yes — decoding happens locally in your browser, so your tokens are never transmitted or stored.

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