Privacy Policy

Last updated: 2026-07-22

This privacy policy describes how the asciiflow web application ("asciiflow", "the app", "we", "us") handles your information when you use it. asciiflow is a browser-based ASCII diagram editor: it lets you draw, edit, and export ASCII-art diagrams, and optionally save them to your own Google Drive.

1. What we collect

The app requests the following Google OAuth scopes when you sign in with Google:

• openid, email, profile — to identify you when you sign in and to address you by name in the UI.
• https://www.googleapis.com/auth/drive.metadata.readonly — to list the ASCII diagrams you have previously saved to your Google Drive so that asciiflow can show them in your diagram list.
• https://www.googleapis.com/auth/drive.file — to create and then delete a tiny temp file in your own Google Drive as a periodic keepalive. Because this is the drive.file scope, asciiflow can only ever see/touch files it created itself.

asciiflow uses incremental authorization: at sign-in it requests only openid, email, and profile. The two Drive scopes are requested separately, only when you explicitly click "Authorize Google Drive access", using include_granted_scopes=true so your existing grants are preserved. Drive access is never requested until you choose to enable it.

1a. What asciiflow reads from your Google Drive

With the drive.metadata.readonly scope, asciiflow reads only the metadata (file name, file ID, and last-modified timestamp) of diagram files that you previously saved through asciiflow in your own Google Drive. asciiflow does not read the contents of any Drive file, does not read files you did not create with asciiflow, and does not read any data outside Google Drive (no Gmail, no Contacts, no Photos, no Calendar).

1b. What asciiflow writes to your Google Drive

With the drive.file scope, asciiflow's background keepalive worker creates one tiny temp file named asciiflow-keepalive-<timestamp>.txt in your own Google Drive every DRIVE_KEEPALIVE_INTERVAL (default 24 hours) and then immediately deletes it. The file exists for only a few seconds. This keeps the Drive API client marked "active" under Google's inactivity policy.

asciiflow only ever creates and deletes its own temp file. It never modifies, overwrites, or deletes files it did not create, never reads any other Drive file, and never writes to any Google Drive account other than yours. The drive.file scope technically prevents asciiflow from even seeing files it did not create.

After a successful sign-in, the app stores locally on the server:

• Your Google account email address (returned by the Google userinfo endpoint).
• The OAuth access token, refresh token, and token expiry returned by Google, so the app can continue to access your saved diagrams without prompting you to sign in again on every visit.

2. How we use the information

• To authenticate your sign-in and restrict access to a configured allowlist of email addresses.
• To list and identify the diagrams you have saved in your own Google Drive (read metadata only).
• To create and then immediately delete a tiny temp file in your own Google Drive as a periodic keepalive (drive.file scope — only files asciiflow created are touched).
• To refresh the access token automatically when it expires, so you remain signed in.

asciiflow does not contain analytics, advertising, or third-party tracking code, and it does not share your data with anyone. Diagrams you save are stored in your own Google Drive account under your control, not on this server.

3. How we store the information

• The OAuth token returned by Google is encrypted at rest with AES-256-GCM before being written to a single file on the server (DATA_DIR/tokens.json).
• The encryption key is supplied via environment variable and is never written to disk by the app.
• The file has 0600 permissions and is owned by a non-root user.
• Tokens are never logged in plaintext; only short non-reversible fingerprints appear in logs.

4. Data retention

The stored token is retained for as long as you want to keep using the app with your Google account. You can revoke access at any time by:

• Visiting https://myaccount.google.com/permissions and removing the app, or
• Stopping the app and deleting DATA_DIR/tokens.json.

5. Data transmission

All communication between your browser, the app, and Google happens over HTTPS. The app listens only on the local loopback interface and is exposed via a TLS-terminating reverse proxy.

6. Your rights

Because the app is self-hosted and stores only OAuth tokens, your main controls are revocation (above) and deletion of the local token file. Your diagrams themselves live in your Google Drive and remain fully under your control via myaccount.google.com.

7. Changes to this policy

If the requested scopes or storage behavior changes, this page will be updated and the "Last updated" date revised.

8. Contact

This is a self-hosted application. For questions, contact the email address configured as ALLOWED_EMAILS on your deployment.