434 tools · free · no sign-up
Developer tools that run in your browser
Most tools process your data locally — FFmpeg, JWT, LLM prompts, PDFs, crypto, images, SEO and more. A few network tools use a small server relay for live requests. All free, no sign-up, no API key.
Browse by category
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
31 tools
Formatters and visual CSS generators
Images
36 tools
Compress, convert and generate images
SEO
11 tools
Previews, meta tags and structured data
Converters
40 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
14 tools
Read, split and convert documents
Video & Media
15 tools
Trim, compress, convert and download video
Dev Utilities
65 tools
Everyday developer helpers
Popular tools
See allBackground 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
Trim, crop, rotate, adjust speed, add fades, filters and a text watermark — export MP4, WebM or GIF in your browser.
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.
DNS Lookup
Network & IP
Query A, AAAA, MX, TXT, NS, CNAME and other DNS records for any domain.
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.
SEO Toolkit
Everything needed to ship a well-optimised page: SERP previews, meta tags, structured data, robots.txt and sitemaps.
Recently added
WHOIS Lookup
Network & IP
Look up domain and IP registration data over RDAP, the modern WHOIS.
SPF / DKIM / DMARC Generator & Checker
Network & IP
Check and build the three DNS records that stop your domain being spoofed.
MX & Mail Server Checker
Network & IP
See which servers accept a domain's mail and whether its policies are set.
Blacklist (RBL) Checker
Network & IP
Check an IP or domain against the major email blacklists at once.
HTTP/2 & TLS Version Test
Network & IP
See which TLS versions a site accepts and whether it serves HTTP/2.
AAB (Android App Bundle) Analyzer
Dev Utilities
Open an .aab file and inspect its manifest, modules, ABIs, densities and size breakdown.