Is Buttercup Safe?

Buttercup — Nerq Trust Score 50.5/100 (C- grade). Score based on 2 independent trust signals. Last analyzed: 2026-03-22

Buttercup is a Firefox extension with a Nerq Trust Score of 50.5/100 (C-), based on 3 independent data dimensions. Last analyzed: 2026-03-22 Security: 90/100. Popularity: 15/100. Data sourced from addons.mozilla.org metadata, permissions analysis, and source code availability. Last updated: 2026-03-22. Machine-readable data (JSON).

Safety Guide: Buttercup

What is Buttercup?

Buttercup is a Firefox add-on — Manage your online identities and credentials with Buttercup: An open-source, free and secure credentials manager..

How to Verify Safety

Review permissions on addons.mozilla.org. Check if source code is available.

You can also check the trust score via API: GET /v1/preflight?target=Buttercup

Key Safety Concerns for Firefox add-on

When evaluating any Firefox add-on, watch for: excessive permissions, data harvesting.

Measured Signals

Buttercup has a Nerq Trust Score of 50/100 (C-). This score is a composite of automated measurements of security, maintenance, community, and quality signals.

Key Takeaways

• Buttercup has a Trust Score of 50/100 (C-).
• The score is a measured composite — it is not a suitability judgment. Evaluate the individual signals against your own requirements.
• Query the current measured values via the Nerq API.

Disclaimer: Nerq trust scores are automated measurements based on publicly available signals. They are not endorsements, verdicts, or guarantees of suitability. Always evaluate the signals against your own requirements.