# What is sent where

Which data the MCP server sends to the fenfill API, and what stays on your machine. The agent's answers are never sent to fenfill or anywhere else.

## What is sent

| Data | Sent to fenfill? |
| --- | --- |
| The blank PDF you analyze | Yes, once (then cached locally) |
| Your API key | Yes, as `Authorization: Bearer` |
| The agent's answers, signatures and the filled PDF | **No, never** |
| Saved templates (blank PDF, fields, your logo) | Downloaded from fenfill to fill locally |
| Page previews (`preview_page`) | **No**: rendered on your machine |
| Layout corrections (`edit_template`) | Only on `save_template`, and then only the layout and the form's own wording |
| Re-analysis (`reanalyze_template`) | Only the template id, pages, kind and version: nothing is uploaded |
| Japanese font download | `GET https://fenfill.com/fonts/NotoSansJP-Regular.ttf`, once, only when a value contains Japanese. Sends no auth and no form data, just a plain GET with a `fenfill-mcp/<version>` User-Agent. Redirects to another host are refused. Checked against a pinned sha256, then cached. |

`analyze_form` refuses PDFs whose form fields already hold answers, and PDFs this server wrote itself, so a filled-in form isn't uploaded by mistake.

## What fenfill keeps

Uploads are encrypted as soon as they arrive on fenfill's servers. Unless you save the form as a template, the blank PDF is deleted when its analysis finishes.

The analysis result is kept for at most 24 hours, or 1 hour after it is first fetched, whichever comes first. After 24 hours the file name is also removed from the job record. Forms you save as templates are kept like any other document. For the full list, see the [privacy policy](https://fenfill.com/privacy).

## What stays on your machine

The MCP server keeps a cache in a folder private to your user: `~/Library/Caches/fenfill-mcp` on macOS, `~/.cache/fenfill-mcp` on Linux, `%LOCALAPPDATA%\fenfill-mcp\Cache` on Windows. Set `FENFILL_CACHE_DIR` to put it elsewhere.

- The cache holds form schemas, blank template PDFs, the workspace logo, hashes of the PDFs it produced and `edit_template` working copies. It never holds the answers you fill in.
- Blank PDFs and the logo are deleted from the cache after 1 hour. Analyses and working copies unused for 90 days are deleted too, and output hashes after a year.
- Filled PDFs are written only where you ask, and are readable by your user only.
- Logs go to stderr and contain tool names, timings and error codes, never field values.
- The Japanese font is stored in the cache and is not aged out.

The first fill with Japanese text downloads the Noto Sans JP font from fenfill.com once. That's a plain file download that carries no form data, and the font stays in the cache.

> **Worth knowing:** Analyzing the same file again is answered from the cache, so nothing is uploaded a second time. `force: true` analyzes it again.

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This is the Markdown version of https://fenfill.com/docs/data-flow.