For Developers, Sysadmins and QA Engineers
88 toolsTools grouped by the jobs of people who build, deploy and support software and websites: check DNS records and redirect chains, decode a certificate and fix its chain, generate test files and secrets, build an ISO image, see what a browser and a device can do. The code utilities — JSON, Base64, regex — open the page.
Developer Tools
JSON Formatter
Beautify, minify, and validate JSON in the browser. Live error line/column, 2/4/Tab indent. Free, no signup.
YAML Formatter
Format, validate, and convert YAML in your browser. YAML ↔ JSON bidirectional, indent options, multi-document support.
HTML Formatter
Beautify or minify HTML in your browser. Indent options, comment removal, void-element handling, preserves <pre>/<script>/<style> content.
MD File Viewer and Editor
Open an .md file and read it as a finished document. Edit, build tables, jump by outline, save to PDF, Word or HTML — in your browser.
JSON ↔ CSV
Convert between JSON arrays and CSV files. Auto-detect direction, configurable delimiter, type coercion, header row toggle. Free, in browser.
Text Diff
Compare two texts side by side. Line, word and character-level diff with insertion/deletion highlighting. Free, in your browser.
Regex Tester
Test JavaScript regular expressions in the browser. Highlight matches, see groups, preview replacement. Free.
JWT Decoder
Decode and inspect JSON Web Tokens in the browser. Header, payload, expiry, claims explained. No signing. Free.
Base64
Encode and decode Base64 in the browser. UTF-8 safe, URL-safe variant, file uploads. Auto-detect direction. Free.
URL Encoder
Encode and decode URL strings in the browser. Component vs full-URL mode, + for space, auto-detect. Free.
Query String
Parse, edit and build URL query strings. Visual table editor, automatic encode/decode, array notation, JSON export.
Hash Generator
Calculate MD5, SHA-1, SHA-256, SHA-384, SHA-512 and CRC32 hashes for text or files in your browser. HMAC, hex or base64.
Hash Identifier
Identify the algorithm behind any hash: MD5, SHA-256, bcrypt, Argon2, NTLM and 50+ more. Ranked matches with hashcat & John modes. Free.
Checksum Calculator
Hash any file with 6 algorithms. Verify downloads, compare files, find duplicates.
UUID Generator
Generate UUID v4 (random), v7 (time-ordered), v1 (timestamp) or Nil UUIDs in your browser. Bulk, formatted, validated. Free.
Slug Generator
Generate URL-friendly slugs from text. Transliterate Cyrillic and Latin diacritics, choose separator, strip stop words, set max length.
Cron Parser
Parse and explain cron expressions. See the next 10 run times in your timezone, with human-readable description and field breakdown.
Font converter
Convert TTF, OTF, WOFF and WOFF2 in any direction, subset by language, pin variable axes and repair vertical metrics. Runs in the browser.
Internet & Security
2 more in this category →DNS Lookup
Look up DNS records for any domain. All record types supported, results from multiple resolvers.
IP Lookup
Look up any IP address or domain to see its location, ISP, VPN status, and more.
WHOIS Lookup
Look up registration details for any domain name including registrar, dates, nameservers, and DNSSEC status.
Redirect Checker
Enter a URL to see the full redirect chain with HTTP status codes, response times, and server details.
IPv6 Test
Test your IPv6 support, detect connection type, compare latency, and check for leaks.
Cookie Checker
Scan any website to discover all cookies, trackers, and privacy risks in seconds.
Speed Test
Check your internet speed: download, upload, ping, jitter and latency under load, over several parallel connections, compared with your plan.
MAC Address Lookup
Identify the manufacturer of any network device by MAC address, generate random MACs for testing, and convert between all standard formats.
What Is My Browser
Instantly detect your browser, OS, screen, hardware, codecs, and web API support. Copy all info for tech support or download a PDF report.
Browser Fingerprint
Estimated entropy per signal, comparison with today's scans, a defense test and fingerprint art — see which signals your browser exposes.
WebRTC Leak Test
Check if WebRTC is exposing your real IP address. Detect local, public, and mDNS candidates with real-time monitoring.
System Diagnostics
Check CPU, GPU, memory, battery, storage, network and browser capabilities. Get a device score, a CPU benchmark and personalized recommendations.
VPN Checker
Check whether your VPN is on and what goes around it: the network websites see, DNS, WebRTC and IPv6 leaks, split tunneling.
Device Testing
Keyboard Test
Test every key, detect ghosting, measure latency and typing speed
Camera Test
Test your webcam for resolution, FPS, sharpness, noise, lighting, and color accuracy.
Codec Support Test
Check which audio and video codecs your browser supports — H.264, H.265, AV1, VP9, Opus, AAC, FLAC. Free, in your browser.
Refresh Rate Test
Measure your monitor refresh rate with precision frame timing. Detect Hz, analyze jitter, explore display capabilities, and test motion smoothness — all in your browser.
What Is My Monitor
Find your screen size, native resolution, refresh rate and monitor model.
Gyroscope Test
Test your phone's gyroscope, accelerometer, and motion sensors. 3D visualization, spirit level, graphs, accuracy test, CSV export.
Vibration Test
Test your device vibration motor with patterns, diagnostics, and a custom builder.
Battery Checker
Free online battery checker.
Phone Display Test
Check your phone screen for dead pixels, touch issues, backlight bleed, burn-in, and color accuracy.
Printer Test
Check your printer in seconds with Quick Test or run detailed diagnostics with Professional mode. Color bars, nozzle check, grayscale, text sharpness, and more.
SSL & certificates
SSL certificate decoder
Read any X.509 certificate: expiry, SAN, issuer, key strength, chain. Explains what is wrong, not only what the fields say.
CSR generator
Create a certificate signing request and its private key in your browser. RSA or ECDSA, every domain in the SAN, no openssl needed.
Self-signed certificate generator
Make an HTTPS certificate for localhost or an internal host. Builds a local CA so the browser warning goes away for good.
Key and certificate matcher
Check whether a private key belongs to a certificate or CSR. Works with RSA and EC, encrypted keys and .pfx bundles.
Certificate format converter
Convert certificates and keys between PEM, DER, PKCS#8, PKCS#1 and PFX. Opens old Windows .pfx exports other tools reject.
Certificate chain fixer
Paste your certificates and get a correctly ordered chain file. Finds the missing intermediate and downloads it for you.
Let’s Encrypt troubleshooter
Find out why certbot cannot validate your domain. Checks DNS, the challenge path over HTTP and your CAA records from outside.
SSL Checker
Enter a domain to inspect its HTTPS certificate: who issued it, when it expires, whether the chain is complete and which TLS versions the server accepts.
Samples & Test Files
2 more in this category →Sample Video Generator
Download or generate sample video for player testing — 1080p / 4K H.264 MP4 catalog plus on-the-fly WebM and MP4 via MediaRecorder.
Sample Audio Generator
Download or generate sample audio for testing — 1 kHz tone, pink noise, custom sine/white/pink at 44.1/48/96 kHz, 16/24-bit, mono/stereo WAV.
Dummy File Generator
Generate dummy files of any size from 1 KB to 10 GB. Zero, random, text or pattern bytes, custom extension, instant browser download.
Test Image Generator
Generate test images for QA — color bars, grayscale, gradient, checker, grid up to 4K. Export as PNG, JPEG or WebP with adjustable quality.
Test PDF Generator
Generate test PDFs in your browser — lipsum text, multi-page sections, big table or blank. A4/Letter/Legal/A3, up to 500 pages, custom title.
Sample Document Generator
Generate sample documents in browser — CSV, JSON, XML, RTF, Markdown, TXT with deterministic rows. Custom row/column count up to 100 000.
Codec Sample Pack
Download codec test files — H.264, H.265 HEVC, AV1, VP9, VP8 in MP4 and WebM. Verify your player and pipeline support with live browser probe.
Corrupted File Generator
Generate corrupted test files for error-path QA — truncate, zero magic bytes, bit-flip, zero middle or rename extension. Browser-based.
Passwords & Secrets
9 more in this category →Password Generator
Password generator with strength meter, pronounceable mode, pattern syntax, bulk export. Cryptographically secure via Web Crypto API.
Passphrase Generator
Memorable passphrase generator using diceware-style word selection. 2048-word list, configurable separators, capitalization, and live entropy.
TOTP Generator
Generate TOTP secrets for two-factor authentication. Live 6-digit code, QR for Google Authenticator / Authy / Aegis, RFC 6238 compliant.
OTP Auth QR Decoder
Decode a Google Authenticator / Authy QR screenshot back into its TOTP secret. Migrate to Aegis, 1Password or any other app. Runs in your browser.
PGP Key Generator
Generate PGP / OpenPGP keys (RSA, Curve25519) in your browser. Encrypt, decrypt, sign and verify. Works with GnuPG, Thunderbird, ProtonMail.
One-Time Secret Share
Share a secret via an encrypted link. AES-GCM 256-bit, decryption key lives in the URL fragment. No account, no database.
Shamir Secret Sharing
Split a secret into N shares where any K of them reconstruct it. Browser implementation over GF(256) for master passwords and seed phrases.
Files & disks
14 more in this category →ISO Creator
Build ISO files from a folder in your browser. Joliet long names, hybrid USB MBR, streamed 8GB+ output via File System Access.
ISO Extractor
Extract ISO files online with UDF and Joliet support. Stream 16GB+ images, preview files in-tree, verify SHA-256 in your browser.
BIN/CUE to ISO
Convert BIN/CUE to ISO online. Auto-detects MODE1/2 sector layouts, extracts CD-DA audio as WAV, parses multi-track cuesheets. In the browser.
Disk Image Inspector
Inspect ISO, VHD, VHDX, VMDK, QCOW2, DMG, E01 disk images. Parse MBR/GPT, detect filesystems, hex view, stream SHA-256.
File diagnosis
Drop the file that will not open — we walk its structure and tell you what is wrong with it.
Secure USB Wipe
Deletes the files you pick, then fills the drive's free space with random data until it is full — the way desktop utilities make deleted files unrecoverable.
Disk image recovery
Drop the image of the card or drive — .img, .dd, .bin, .raw.
Text Tools
Archives
1 more in this category →Images
Color Picker from Photo
Upload a photo and drag across it — the loupe shows the exact pixel while the tool reads the color in six formats, names the shade and finds the nearest RAL.
Screenshot Beautifier
Add device or browser frames, gradient backgrounds, shadows and rounded corners to screenshots. Razor-sharp 2x/4x PNG export. In your browser.
QR & barcodes
3 more in this category →Robotics
Calls & sharing
Other tools
Unix Timestamp Converter
Convert Unix timestamps to ISO 8601, UTC, RFC 2822 and relative time, or any date back to epoch seconds. Batch mode and live counter. Free.
Color Converter
Convert between HEX, RGB, RGBA, HSL, HSLA, HWB, LAB, LCH and OKLCH. Shade and tint palette, WCAG contrast check, eyedropper.
Flowchart
Flowchart editor: Mermaid text and mouse in one window, diagrams from a description or from code. Block nudges stay put. PNG, SVG, PDF.
Color Accessibility Checker
Pick two colors to check contrast ratio and colorblind visibility.
Colorblind Simulator
Upload an image to compare original and colorblind views side by side.