katlab tools
Small, free web utilities that run entirely in your browser.
No uploads · no accounts · no tracking
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Files, media & PDF
Zip & Unzip
Create ZIP, 7z or TAR.GZ, edit an existing ZIP, or unzip — locally, no upload.
Image Convert
PNG · JPG · WebP conversion and resize — locally, no upload.
HEIC to JPG
Convert iPhone HEIC & HEIF photos to JPG, PNG or WebP — locally, no upload.
PDF Tools
Merge PDFs into one or split out pages — locally, no upload.
Organize PDF
Preview, rotate, delete & reorder PDF pages — locally, no upload.
Annotate PDF
Draw, highlight, sign & truly redact PDFs — locally, no upload.
Sign PDF
Draw, type or upload a signature & place it on any page — locally, no upload.
Compress PDF
Shrink scanned & image-heavy PDFs 4–10× — locally, no upload.
Unlock PDF
Remove PDF restrictions & known open passwords — locally, no upload.
Image Compress
Shrink JPG, PNG & WebP — lossless, near-lossless or lossy — locally, no upload.
Video Compressor
Shrink MP4 video by quality or to a target size — locally, no upload.
Video to GIF
Turn any video clip into an animated GIF — locally, no upload.
Images to GIF
Turn images into an animated GIF with transitions & loop control — locally, no upload.
Images to Video
Turn photos into an MP4 slideshow with transitions, no watermark — locally, no upload.
Video Trimmer
Cut a clip instantly (no re-encode) or frame-exact — locally, no upload.
Audio Converter
MP3, WAV, OGG, FLAC, M4A — convert, trim or extract from video — locally, no upload.
Video to MP3
Pull the MP3 soundtrack out of MP4, MOV & WebM — locally, no upload.
SRT ↔ VTT Converter
Convert subtitles both ways + time-shift resync — locally, no upload.
Images to PDF
Combine JPG, PNG & WebP into a single PDF — locally, no upload.
PDF to PowerPoint
Every PDF page becomes a PPTX slide, pixel-perfect — locally, no upload.
PDF to JPG
Convert PDF pages to JPG or PNG images — locally, no upload.
Markdown to PDF
Polished PDFs from Markdown with themes, code & math — no watermark, no upload.
PDF to Markdown
Turn a PDF into clean Markdown with headings & lists — locally, no upload.
Images to PowerPoint
Turn JPG & PNG photos into PPTX slides — locally, no upload.
QR Code Generator
Turn a link or text into a QR code — download PNG or SVG, no upload.
Barcode Generator
Code 128, EAN-13, UPC-A & more — SVG or PNG, no upload.
Archive Extractor
Open RAR, 7z, ISO, DMG, EXE installers & more — browse, preview, convert. No upload.
Email File Viewer
Open EML, MSG, MBOX, PST & winmail.dat — read mail, save attachments. No upload.
Favicon Generator
Make favicon.ico & PNG sizes from any image — locally, no upload.
SVG to PNG
Rasterize SVG to crisp PNG at any scale — locally, no upload.
Image to SVG
Vectorize line art & logos, B/W or colour, to SVG, PDF or DXF — locally, no upload.
SVG Optimizer
Minify SVG with SVGO, safe defaults + live preview — locally, no upload.
EXIF Metadata Remover
Strip GPS & camera data from JPG, PNG & WebP — locally, no upload.
Developer & text tools
Color & Contrast
WCAG contrast checker + HEX/RGB/HSL/OKLCH converter — no upload.
JSON Formatter
Beautify, validate & minify JSON — locally, no upload.
JSON to Types
Generate TypeScript, Go, Rust & Python types from JSON — locally, no upload.
SQL Formatter
Beautify & minify SQL — MySQL, Postgres, SQLite & more — locally, no upload.
SQLite Playground
Run real SQL on your CSV & JSON with SQLite — locally, no upload.
Base64 Encode / Decode
Convert text or files to and from Base64 — locally, no upload.
Hash Generator
MD5, SHA-1, SHA-256 & SHA-512 of text or files — locally, no upload.
UUID Generator
Random v4 UUIDs, single or in bulk — locally, no upload.
JWT Decoder & Verifier
Decode, verify & sign JSON Web Tokens, generate JWKs — locally.
cURL to Code
Convert a curl command to Python, fetch, Go & more — locally, no upload.
Case Converter
camelCase, snake_case, kebab-case & more — locally, no upload.
CSV / JSON Converter
Convert CSV to JSON and back, RFC 4180 — locally, no upload.
JSON Escape / Unescape
Text to JSON string literal and back, \uXXXX option — locally, no upload.
jq Playground
Run real jq filters over JSON, live — locally, no upload.
YAML ↔ JSON Converter
Convert YAML to JSON and back, multi-doc aware — locally, no upload.
XML Formatter
Format, validate & convert XML ↔ JSON — locally, no upload.
HTML ↔ Markdown
Convert HTML to clean Markdown and back, GFM tables — locally, no upload.
Regex Tester
Test regular expressions with live match highlighting — no upload.
Cron Parser
Crontab schedules in plain English + next run times — locally, no upload.
Timestamp Converter
Unix epoch to date and back, any time zone — locally, no upload.
Diff Checker
Compare two texts by line, word or character — locally, no upload.
Text Compression
Gzip, deflate or LZ-string text to Base64 & back — no upload.
.NET Ticks Converter
C# DateTime.Ticks to date and back, exact BigInt math — no upload.
URL / HTML Entity Encode
Percent-encode URLs & escape HTML entities — locally, no upload.
Password Generator
Strong random passwords, crypto-secure — locally, no upload.
File Encryptor
Encrypt any file with a passphrase, AES-256-GCM — locally, no upload.
Subnet Calculator
CIDR, netmask & host ranges for IPv4 and IPv6, plus a subnet splitter.
Decode Anything
Auto-detects and peels nested Base64, URL, hex, HTML & gzip layers.
Certificate Decoder
Inspect X.509 / PEM certificates — SANs, expiry, fingerprints, chains.
SSH Key Generator
Ed25519, ECDSA & RSA keys in OpenSSH format — generated locally.
htpasswd Generator
bcrypt & apr1 lines for Apache / nginx basic auth, plus verify.
CSP Builder
Build & audit a Content-Security-Policy, export for any server.
Log Redactor
Mask emails, IPs, cards & API keys in logs before you share them.
TOML Converter
TOML ↔ JSON ↔ YAML, live, with datetime-safe round trips.
Mermaid Editor
Live Mermaid diagrams with SVG & PNG export and share links.
Token Counter
Exact GPT token counts, token view & LLM cost estimates.
CSS Gradient Generator
Linear, radial & conic gradients with draggable stops & OKLCH.