Questions
What is Sponge?
Section titled “What is Sponge?”A reading library. You save articles and PDFs, a computer you control captures a readable copy, and you read, highlight and take notes in a browser, on a Mac or from a terminal. Search, export and a coding-agent interface work on the same library. How Sponge works has the full picture.
Do I need an account?
Section titled “Do I need an account?”Not for the command line. sponge captures, searches, highlights, exports and backs up a local library with no sign-in. You need an account for sync, the web library, the apps, saving from other devices and public pages.
Is it free?
Section titled “Is it free?”The command and the local library are free with no item limit. The cloud is free for 100 saved items per account. Sponge Plus removes that limit for $5 a month on the web. At the limit, what is already synced stays readable, searchable and exportable, and new items wait on your computer. See Sponge Plus.
I saved a link. Why is it not in my library?
Section titled “I saved a link. Why is it not in my library?”Saving from the web library, the Mac app, Chrome or a phone adds the link to a queue. A computer running sponge and signed in to your account has to capture it. Run sponge sync there, or keep sponge sync --watch or the background worker running. Save in the web library shows the queue and whether a computer is connected. See Ways to save.
Can I use Sponge with only a phone or only a browser?
Section titled “Can I use Sponge with only a phone or only a browser?”You can read, search, highlight and take notes on what is already in your library, and queue new links. You cannot capture: that needs a Mac or Linux computer running sponge, even one that is only on some of the time.
Which platforms are supported?
Section titled “Which platforms are supported?”The command runs on macOS and Linux with Node.js 24.20 or newer. Windows is not supported. The web library runs in a current browser. The Mac app needs macOS 15. Some model features need an Apple Silicon Mac; Requirements and platforms has the table.
Are the iPhone app and the Chrome extension available?
Section titled “Are the iPhone app and the Chrome extension available?”Yes. The Mac app is at sponge.computer/mac, the iPhone and iPad app is on the App Store, and Sponge for Chrome is on the Chrome Web Store. The web library also works in any phone browser.
Is my library private? Is it end-to-end encrypted?
Section titled “Is my library private? Is it end-to-end encrypted?”Items are private unless you publish or share them. The local library stays on your computer. If you sync, the cloud stores the text of your saves, highlights and notes, protected in transit by TLS and at rest by the storage provider. It is not end-to-end encrypted: the service can technically read synced text. If that matters for some material, keep it in a local library that you do not sync. The privacy policy lists what is stored.
Does Sponge send my reading to an AI service?
Section titled “Does Sponge send my reading to an AI service?”No. Summaries, speech recognition and embeddings run in models on your own computer, and search by meaning in the web library runs in the browser tab. The cloud runs no model.
Can I import from Pocket, Instapaper or Readwise?
Section titled “Can I import from Pocket, Instapaper or Readwise?”No. There are no importers for those services. You can add links one at a time or from a script with sponge add URL or sponge saves add URL. The sponge import command reads only Wordcell and Jungle captures; see Import Wordcell and Jungle captures.
What about images, PDFs, video and pages behind a login?
Section titled “What about images, PDFs, video and pages behind a login?”- Images are not copied to the cloud. The reader loads them from the publishing site, so an image the publisher removes will be missing.
- PDFs are captured as text on your computer and need Poppler. The PDF file itself does not sync.
- Video and audio transcripts need an Apple Silicon Mac with macOS 26, where
sponge setup --captureinstalls the media helper. - Pages behind a login can be captured through your own signed-in browser with
sponge add URL --browser, on macOS only.
How does Sponge compare with a hosted read-later service?
Section titled “How does Sponge compare with a hosted read-later service?”A hosted service captures on its servers, so saving from a phone works with nothing else running, and it usually ships polished mobile apps, importers and browser extensions for every browser.
Sponge is weaker there. Capture needs your own computer to be on at some point. There is no Android app, no Firefox or Safari extension, no importer from other services, no text-to-speech and no email or newsletter inbox. Review of summaries happens in a terminal.
What you get in exchange: the library is a SQLite database and files on your disk that you can back up, export as Markdown and query from scripts or a coding agent. Capture and models run on your hardware. The local library has no item limit and no subscription. The cloud holds text only and can be left out entirely.
How do I get my data out?
Section titled “How do I get my data out?”sponge export ITEM --output /absolute/folder # one item as Markdown, with images and notessponge backup --output /absolute/library.sponge # the whole librarysponge restore /absolute/library.sponge --into /absolute/new-libraryThe highlights notebook in the web library exports all highlights and notes as Markdown.
How do I delete my account?
Section titled “How do I delete my account?”Signed in, open Account and choose Delete account. Local libraries on your computers are not touched. Deleting your account describes what is erased.
Where do I get help?
Section titled “Where do I get help?”Write to the address on the support page.
Documentation drafted with AI and checked against the product source.