Free online developer tools

Drag curve handles to design CSS easing functions and preview the motion.

Builds frosted-glass CSS effects with live preview.

Creates pure CSS spinners and loading bars with adjustable style.

Designs toggle switches in pure CSS.

Produces CSS border-trick triangles and arrows.

Draws a railroad diagram of a regex and highlights how it matches your sample text.

Converts Unix timestamps to human dates and back, with code snippets for many languages.

Flashes ESPHome firmware to a board over USB from the browser.

Colours a pasted PostgreSQL EXPLAIN plan to highlight the slowest nodes.

Generates syntactically valid but random IBANs for testing forms.

Free REST API returning sample store products, carts and users for demos and front-end practice.

Explores binary layouts of float formats such as half, single, double and bfloat16.

Generates Brazilian postal codes (CEP) for form testing.

Generates syntactically valid CNH driver licence numbers for tests.

Generates valid Brazilian CNPJ company numbers for test data.

Generates valid Brazilian CPF numbers for software testing.

Generates fictional Brazilian company documents (CNPJ, state registration, CEP).

Generates fictional Brazilian person records (name, CPF, RG, address) for testing.

Generates Renavam vehicle registration numbers for testing.

Generates RG identity numbers following SSP-SP format for testing.

Runs and shares code snippets in dozens of languages from the browser.

Opens a file and lets you inspect and edit its bytes in a hex view.

Edits binary files byte by byte in a browser hex editor.

Browser MQTT client for publishing and subscribing against HiveMQ or your own broker.