AudioMass
audiomass.co
A waveform audio editor that runs in the tab with nothing uploaded
No sign-upOn device
Websites tagged “open source”
13 sites in AltF Atlas are tagged open source, spanning 9 categories. 8 of them work with no account at all, and 6 process your files in the browser without uploading them. Every entry states where its free version stops.
13 sites8 need no sign-up6 on device
Cal.com
cal.com
Open-source scheduling links you can run on your own server
Free tierDeepSeek
deepseek.com
Open-weight reasoning model you can use free in a chat window
Free accountExcalidraw
excalidraw.com
Hand-drawn-looking whiteboard that opens instantly with no sign-up
No sign-upOn deviceHugging Face Spaces
huggingface.co
Thousands of runnable AI demos, no model installed on your machine
No sign-upInvoice Ninja
invoiceninja.com
Open-source quotes and invoices you can host on your own server
Free tierJitsi Meet
meet.jit.si
Open-source video meetings guests join in a browser with nothing installed
Free accountLanguageTool
languagetool.org
Open-source grammar checking across more than twenty languages
No sign-upMarkmap
markmap.js.org
Turns a Markdown outline into a collapsible mind map as you type
No sign-upOn deviceRAWGraphs
rawgraphs.io
Makes the chart types nothing else offers — alluvial, beeswarm, treemap
No sign-upOn deviceStirling PDF
stirlingpdf.io
Fifty PDF tools you can also run on your own machine in Docker
Free tiertldraw
tldraw.com
Infinite canvas that feels like a native app in a browser tab
No sign-upOn deviceVERT
vert.sh
Open-source converter that handles images, audio and documents on your device
No sign-upOn device
Cuts across
Categories this tag spans
A tag is orthogonal to the category tree — that is what makes it worth having.