Free online browser tools
Free tools that run 100% in your browser - no install, no account, and your data is never uploaded (Google Analytics for visit stats only - verify it yourself).
- GNSS Monitor - live GPS/GNSS viewer for external Bluetooth and USB receivers: satellite sky plot, per-satellite signal bars, NMEA decode plus u-blox UBX framing with NAV-PVT decode. Works on Android phones (Chrome) and desktop. How to use
- HyperTerminal online - the long-lost Windows serial terminal, reborn on the Web Serial API: COM properties, capture to file, send text file. How to use
- AT Command Tester - talk to GSM/LTE modems and IoT modules: click-to-send command catalog, script runner, parsed signal/registration status. How to use
- Hex viewer/editor - open any file, edit bytes in place, search by hex, text, numbers (u8..i64, little/big endian) or bit sequences at any bit offset. How to use
- GIS format converter - GDAL
ogr2ogrcompiled to WebAssembly: convert Shapefile, GeoJSON, GPX, KML, GeoPackage, CSV, DXF, FlatGeobuf and more, with optional EPSG reprojection - your survey data is never uploaded. How to use - Static QR code generator - your URL/WiFi/contact is encoded directly into the QR: no redirect through anyone’s server, so it never expires and can’t be paywalled later. PNG and SVG export, UI in 12 languages (English, ไทย, 中文, all ASEAN, Español, Português). How to use
- Audio extractor & converter - ffmpeg compiled to WebAssembly: extract audio from video (MP4→MP3), convert between MP3, WAV, FLAC, OGG, Opus, M4A - recordings stay on your machine. Honest limit: ~10-20x slower than desktop ffmpeg, 500 MB cap. How to use
- doctor - the classic Emacs ELIZA psychotherapist: reach your own answer, no AI needed. How to use
- calc - Emacs-style RPN stack calculator with the bindings your fingers remember. How to use
- isearch - Emacs-style incremental search over any pasted text or file. How to use
All open source: web_gnss, hyperterminal, web_at, web_fun. Feedback and bug reports are very welcome - comment on the how-to posts or open a GitHub issue.
Full disclosure: this post - and any code or tool it describes - was co-authored with Claude (Anthropic’s AI, via Claude Code). I directed, reviewed and tested; Claude wrote most of the code and most of the text. I don’t want to pretend otherwise.