spongeInstapaper’s export gives you a list of links, not your reading: the CSV has no article text, highlights, or notes. Sponge keeps those together, in a private library your own AI agent can research from.
Instapaper is still running. It is a focused read-it-later app that saves articles and videos for reading on the web, iOS, and Android. Its Premium plan, $5.99 a month or $59.99 a year, adds full-text search, a permanent archive, unlimited notes, a PDF reader, Kindle integration, text-to-speech playlists, and an ad-free site. Sponge is a private library for articles and PDFs. It keeps a readable copy of each page you save with your highlights and notes attached, and your agent reaches those sources through a scoped HTTP API or a local MCP server.
Status: Preview. Sign in at sponge.computer to save a public link or a PDF, and see Status and limits for which parts are verified and which are still being checked.
Where Instapaper and Sponge differ
- Exports. Instapaper’s account export emails you a CSV of your saved links with the URL, title, the text selected at save time, folder, timestamp, and tags. Article text, highlights, and notes are not in it. You can also download a reading list as a PDF or ePub bundle, but it includes only the first 19 articles. Sponge exports each saved source as a bundle of the original bytes, the capture records, and your annotations, each file verified by checksum.
- Search. Full-text search in Instapaper requires Premium. In Sponge, library search is part of the API and the browser library at no extra cost.
- Notes and highlights. Instapaper’s free tier allows five notes a month, and Premium removes the limit. In Sponge, notes and highlights attach to the saved copy’s text. A highlight anchors to a specific passage, and Sponge refuses a selection that does not match it.
- Agent access. Instapaper offers a third-party API on its free tier for saving and listing. Sponge’s API is built for agents. It issues scoped credentials that expire, requires an idempotency key on every write, makes document edits name the revision they build on, and includes a local MCP server that exposes the library commands as tools.
- What you can save. Instapaper saves articles and videos. Sponge saves public web pages, PDFs with extractable text, and supported text files up to 12 MiB each. It does not capture video or pages that need a sign-in.
When Instapaper is the better choice
- You want a small, quiet reading app with mobile apps, Kindle sends, text-to-speech, and speed reading.
- You do not need an agent to work from your saves, or the CSV and the API are enough for your tools.
- Full-text search and a permanent archive are worth $5.99 a month to you.
When Sponge is the better choice
- You want to keep the saved copy, your highlights, and your notes in one private place, so an agent can cite them as sources.
- You want to write with an agent from those sources, with each edit versioned and each claim checkable against the saved text.
- You want to read your library through a scoped API as well as the app.
Moving an Instapaper library
The CSV export is the way out, and it carries links only. Read the URL column and run each row through Sponge’s save-link command, using the loop described in Move a Readwise Reader library to Sponge; only the export step differs. Article text, highlights, and notes do not come across, because the export does not contain them.