444 tools · free courses · extensions

Free developer tools, tech courses & resources

444 private browser tools, interactive animated coding courses, and developer extensions. Fast, free, and no sign-up.

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AI & LLM

23 tools

Tokens, prompts, RAG and tool schemas

API & HTTP

16 tools

OpenAPI, REST clients, webhooks and sockets

JSON

16 tools

Format, validate and convert JSON

Text & String

43 tools

Count, convert, clean and compare text

HTML & CSS

32 tools

Formatters and visual CSS generators

Images

38 tools

Compress, convert and generate images

SEO

13 tools

Previews, meta tags and structured data

Converters

41 tools

Convert between data formats and units

Encoders & Crypto

22 tools

Encode, decode, hash and encrypt

Generators

13 tools

Generate IDs, data and boilerplate

Date & Time

15 tools

Timestamps, timezones and durations

Network & IP

31 tools

IP, subnets, headers and URLs

Color

9 tools

Convert, mix and check colors

Math & Numbers

17 tools

Calculators and number utilities

Security

17 tools

Audit secrets, headers and policies

PDF & Documents

16 tools

Read, split and convert documents

Video & Media

16 tools

Trim, compress, convert and download video

Dev Utilities

66 tools

Everyday developer helpers

Free tech courses

Animated, beginner-friendly lessons. Your progress is saved in this browser.

All courses

Python

13 chapters

Python Mastery: Zero to Production

See how Python really thinks — memory, loops and async, animated.

Start Chapter 1 →

Chapters soon

Generative AI & LLM Engineering

Tokens, embeddings, RAG and agents — explained with playable visuals.

Coming soon

Data

Chapters soon

Data Analytics & Business Intelligence

From messy spreadsheets to dashboards and SQL insights.

Coming soon

Systems

Chapters soon

Modern System Design & API Architecture

Watch requests travel through caches, load balancers and queues.

Coming soon

DevOps

Chapters soon

Cloud, Containers & DevOps

Docker, CI/CD and Kubernetes made visual.

Coming soon

Web

Chapters soon

Modern Full-Stack & React Internals

How React renders, updates and talks to the server.

Coming soon

Chapters soon

Machine Learning Foundations

Regression, trees and neural networks you can poke and tweak.

Coming soon

Systems

Chapters soon

Cybersecurity Essentials for Developers

See attacks happen — then learn to stop them.

Coming soon

Browser extensions

All extensions

WebP/AVIF Image & Audio Converter

Save WebP/AVIF images as PNG or JPG and send media to Coders Hub tools.

API Inspector

See API calls, view JSON, replay requests and copy them as cURL.

M3U8 & MP4 Video Link Detector

Find HLS, DASH and direct video links on any page.

Popular tools

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Background Remover

Images

Erase the background from a photo and export a transparent PNG.

Online Notepad++

Text & String

A tabbed code and text editor with syntax colours, find and replace, and auto-save.

M3U8 / HLS Downloader

Video & Media

Download an .m3u8 HLS stream and save it as a single MP4 file.

Video Editor

Video & Media

Edit video with a live preview: visual trim timeline, aspect crop, colour, text overlay and background music — export MP4, WebM or GIF in your browser.

PDF Viewer & Editor

PDF & Documents

View, search, annotate, redact, number and export PDF files offline.

JSON Formatter

JSON

Pretty-print and beautify JSON with custom indentation.

Word Counter

Text & String

Count words, characters, sentences, and reading time.

App Icon Generator (iOS, Android & Web)

Images

One image in, a ready-to-copy icon pack out for iOS, Android, web, macOS, Windows and extensions.

Image Editor

Images

Crop, rotate, filter, annotate and layer images with text, watermarks and overlays — all in your browser.

Why use Coders Hub?

Private by design

Your data never leaves the tab. No uploads, no accounts, no tracking of what you paste.

Works offline

Tools run on browser APIs, so they keep working once the page has loaded.

Instant results

No round-trips, no spinners. Output updates as fast as you type.

Curated collections

Frontend Toolkit

Everything a frontend developer reaches for daily: CSS generators, HTML formatters, JSON utilities and image optimisation.

Backend Toolkit

Payload wrangling for API work: JSON formatting, validation, conversion and text transformation.

Android Toolkit

Assets and payloads for Android development: icon and image generation, JSON handling and colour utilities.

iOS Toolkit

Everything for shipping an iPhone or iPad app: Swift models, plist and .strings conversion, universal links, privacy manifests, app icons and screen size references.

DevOps Toolkit

Config and payload tools for pipelines: YAML and JSON conversion, diffing, minification and validation.

Documents & Spreadsheets

Edit spreadsheets, documents and PDFs offline: XLSX Studio, CSV editor, Document Editor, PDF viewer/editor, OCR text and table extraction, merging and conversion.

Recently added

Python Playground — Run Python Offline

Dev Utilities

Run real Python 3 in your browser with NumPy, Pandas, Matplotlib, scikit-learn and more.

CSS Cubic-Bézier & Spring Physics Studio

HTML & CSS

Shape easing curves and physical springs with live animation previews.

SVG Path Visual Inspector & Editor

Images

Visualise, drag-edit, transform and minify SVG path d data in your browser.

SRT & VTT Subtitle Time Shifter & Editor

Video & Media

Shift subtitle timing, fix drift and fps mismatch, edit cues and convert SRT ↔ VTT.

XLSX Studio — Excel Viewer & Editor

PDF & Documents

Open, edit and save Excel workbooks offline — 50+ formulas with autocomplete, filters, conditional formatting, charts and PDF export.

SQL DDL to TypeScript / Zod / Prisma / Drizzle

Converters

Generate TypeScript, Zod, Prisma, Drizzle, JSON Schema and an ER diagram from CREATE TABLE SQL.