Free Online Developer Tools — 29 Browser-Based Utilities

cURL → Code Converter

Turn a curl command into fetch, Python, or other client code.

Cron Expression Builder

Build and explain cron schedules in plain English.

Timestamp & Timezone Converter

Compare a time across zones on a visual hour grid, and convert epoch / ISO 8601 / RFC 2822 timestamps.

Bulk Case Converter

Convert text between camelCase, snake_case, kebab-case, and more.

JSON to String Converter

Escape JSON into a string literal, or unescape it back — runs entirely in your browser.

String to JSON Converter

Convert an escaped string back into valid, readable JSON instantly. Free, runs entirely in your browser — nothing is uploaded.

JS, CSS & JSON Minifier

Strip whitespace, comments, and unnecessary characters from JavaScript, CSS, or JSON.

Webhook / Request Bin

Capture and inspect incoming HTTP requests.

CORS Debugger

Diagnose why a cross-origin request is being blocked.

JWT Decoder & Verifier

Decode a JWT's header/payload and check its signature.

HTTP Status Code & Header Reference

Look up status codes and header meanings.

SSL Certificate Checker

Inspect a host's TLS certificate chain and expiry.

Regex Tester & Explainer

Test a regex against sample text with a plain-English breakdown.

Diff Checker (Text & JSON)

Compare two blocks of text or JSON side by side.

Markdown Table Generator

Paste CSV, get a formatted Markdown table.

Realistic Fake Data Generator (India)

Generate realistic sample data for India-specific fields.

Color Palette Extractor + Contrast Checker

Extract colors from an image and check WCAG contrast.

Fluid Typography (clamp()) Calculator

Generate a responsive clamp() font-size formula.

Box-Shadow / Gradient / Border-Radius Generators

Visually build common CSS effects and copy the code.

Favicon Generator

Generate a full favicon set from one image.

.env File Validator

Catch missing keys, malformed lines, and likely secrets.

Password / API Key Generator

Generate strong passwords/keys with an entropy meter.

README Generator

Build a polished README.md from a form.

.gitignore Generator

Pick your stack and get a merged, de-duped .gitignore.

Open Graph / Meta Tag Preview

Preview link cards on Twitter, LinkedIn, Slack, and more.

Profit Margin Calculator

Calculate selling price from cost price and margin, or margin/markup from cost and selling price.

Payment Reminder Generator

Generate a professional payment reminder for email, WhatsApp, or SMS — tone adjusts to how overdue the invoice is.

Quotation / Estimate Generator

Create a professional quotation or estimate with line items, discounts, and optional tax breakup.

GST Invoice Generator

Create a GST-compliant invoice with automatic CGST/SGST or IGST split, amount in words, and PDF export.