# Requirements and platforms

Sponge captures on a computer and reads anywhere with a browser. This page says what each platform can do today, and which features need a model download or a native helper.

## A computer running `sponge`

Install with `npm install -g @hraness/sponge`. The command needs Node.js 24.20 or newer on macOS or Linux. Windows is not supported.

| Capability | macOS | Linux | Needs |
| --- | --- | --- | --- |
| Save articles | Yes | Yes | Nothing extra |
| Save PDFs | Yes | Yes | Poppler (`pdfinfo`, `pdftohtml`); Tesseract for optional OCR |
| Read, list, keyword search | Yes | Yes | Nothing extra |
| Highlights, notes, export, backup, restore | Yes | Yes | Nothing extra |
| Sync, save queue, public pages | Yes | Yes | A Sponge account |
| MCP server and JSON CLI for agents | Yes | Yes | Nothing extra |
| Summaries | Apple Silicon, macOS 26 | x64 or ARM64 with glibc | `sponge setup --digest` and 16 GiB of memory |
| Summaries with your own model server | Yes | Yes | A server on `127.0.0.1` |
| Background worker installed as a service | Yes (`sponge worker install`) | Run `sponge worker foreground` under systemd | Nothing extra |
| Signed-in pages through your browser | Yes (`sponge browser setup`) | No | A Chromium browser and the capture extension |
| Media transcripts | Apple Silicon, macOS 26 | No | `sponge setup --capture` |
| Local speech recognition, English | Apple Silicon, macOS 26 | No | `sponge setup --asr` |
| CLI semantic search | Apple Silicon, macOS 26 | No | `sponge setup --embedding` |
| Building the library map | Apple Silicon, macOS 26 | No | `sponge setup --embedding` and the summary model |

### Summaries

`sponge setup --digest` downloads a pinned llama.cpp build and one model from their public sources and verifies their hashes.

| Memory | Model | Download |
| --- | --- | --- |
| 16 GiB to 32 GiB | Qwen3.5 9B | About 5.6 GB |
| 32 GiB or more | Gemma 4 26B-A4B | About 16.9 GB |

On Linux the managed model server also needs bubblewrap with user and network namespaces, glibc 2.35 or newer on x64, and glibc 2.39 or newer on ARM64. [Linux](/docs/linux) has the package list. With less than 16 GiB, run a smaller model yourself and pass its loopback address; [Summaries](/docs/summaries) shows how.

### Native helpers

Media transcripts, local speech recognition, CLI semantic search and library-map building use native helpers built for Apple Silicon Macs on macOS 26. The helpers ship inside the `sponge` package, and `sponge setup --capture`, `--asr` and `--embedding` install them with no account or token. Setup downloads only public files: the speech and embedding models from Hugging Face, and the embedding library from LiteRT-LM's release on GitHub. Every file is checked against the hashes in the package before it is used. A package from before 0.28.0, or a source checkout, has no helpers and reports `runtime-missing`.

Everything else on this page works without them. `sponge search` falls back to keyword search and says so, and the web library has its own search by meaning that needs no helper.

## Where you read

| Surface | Requires | Status |
| --- | --- | --- |
| Web library at [account.sponge.computer/library](https://account.sponge.computer/library) | A current browser that allows private site storage | Available |
| [Sponge for Mac](/docs/mac) | macOS 15 or later | Available at [sponge.computer/mac](https://sponge.computer/mac) |
| Sponge for iPhone and iPad | iOS 17 or later | Available on the [App Store](https://apps.apple.com/app/id6832334929) |
| Sponge for Chrome | Chrome 116 or later | Available on the [Chrome Web Store](https://chromewebstore.google.com/detail/sponge-for-chrome/afljoicpnoojmmaabiiecfbedpkomihf) |

The Mac and iPhone apps show the web library, so the table below applies to all three.

| In the web library | Works for everyone | Notes |
| --- | --- | --- |
| Reading, filing, reading progress | Yes | Offline once the browser's copy has loaded |
| Keyword search | Yes | Runs in the browser |
| Search by meaning | Yes | A model of about 4 MB loads with the page; ranking happens in the tab |
| Highlights, notes, notebook export | Yes | Edits made offline are sent later |
| Saving a link | Yes | A computer running `sponge` captures it |
| Sharing and public pages | Yes | See [Sharing and publishing](/docs/sharing) |
| Summaries on an item | When one of your computers drafted it and you accepted it | See [Summaries](/docs/summaries) |
| Library map | When one of your computers built a map | Building needs an Apple Silicon Mac, as above; viewing does not |

A browser that cannot keep its own copy of the library, such as some private windows, cannot open the library. Account settings, the save queue and device management still work there.