What Tampermonkey is

Tampermonkey installs, edits, updates, and toggles userscripts: small programs that change page layouts, add features, or automate actions on the sites they match. The listing documents script sync through Chrome Sync and cloud storage such as Google Drive, Dropbox, OneDrive, and WebDAV, plus zip and cloud backups.

Feature coverage

  • Userscript editor and one-click script toggles
  • Automatic userscript updates
  • Sync and backup via Chrome Sync or cloud storage

What stands out

  • Very large, long-running public record
  • Updated in October 2026
  • Developer-maintained blacklist flags problem scripts

Tradeoffs to know

  • Current versions are closed source
  • Each userscript inherits broad page access
  • Chrome needs the Allow User Scripts toggle or Developer Mode

Is Tampermonkey safe to use?

Yes, for the manager itself: Tampermonkey has a long public record, a named developer, current updates, and a listing that describes its disclosed data as anonymous statistics you can switch off. The risk lives in userscripts, which run with the page access you grant, so install only scripts you can read or trust.

Page access Broad

Requests page-content access across sites. Broad access is not itself a red flag — the question is whether the job justifies the reach, and whether the publisher's record earns it.

Tampermonkey requests access to all sites because, as its FAQ explains, it cannot know in advance where your userscripts will run; each script's match rules then decide where it acts. In Chrome, version 5.3 and later also needs the extension's Allow User Scripts toggle or Developer Mode before scripts run. Read a script's match rules and code before installing it.

Store-disclosed data

  • Location
  • User activity

The listing discloses location and user activity. The developer describes these as anonymous usage statistics (extension version, language, browser and OS type, script installs used for blacklist updates) plus error reports, with truncated IP addresses in server logs. Turning off Anonymous statistics stops this, and nothing is sent in incognito mode. Userscripts can send data wherever their own code allows.

Why does Tampermonkey need access to all websites?

Its FAQ says it has to be able to run on every page because it cannot know where your userscripts will run. Each script's match rules then limit where it acts, and a script can read or change the pages it matches, which is why a script's source deserves a look before you install it.

Does Tampermonkey collect my data?

The listing discloses location and user activity. The developer says this covers anonymous usage statistics and error reports, that server logs keep only truncated IP addresses, and that nothing is collected in incognito mode. The Anonymous statistics setting turns it off, and blacklist and update-notification checks can be disabled too.

Is Tampermonkey open source?

No. The developer's GitHub repository holds GPLv3 source only up to version 2.9 and states that all newer versions are distributed under a proprietary license. Current Tampermonkey is free to use, but its code is not published for outside review.

How we judge this: our extension safety guide · how we rate

Pricing

Free to use; closed-source freeware with optional donations. Pricing and plan limits change more often than store metadata, so use the linked developer page as the final check before subscribing.

Alternatives

AlternativeStylusAlternativeRefined GitHub

Sources

We used the official Chrome Web Store listing and first-party developer material. Public metrics can change after the fact-check date.

  1. Chrome Web Store listing

    Rating, rating count, public users, version, update date, and publisher disclosures verified 2026-10-12.

  2. Tampermonkey product documentation

    First-party product, feature, support, or project documentation used for workflow context.

  3. Extension Reviewer methodology

    How public claims, permissions, evidence, and tradeoffs are reviewed.

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