What is trustd on a Mac, and why is it using CPU?
trustd checks certificates for every secure connection and signed app. Two copies run. On our Mac it showed an energy impact of 1.4. When it spikes and why.
What is trustd?
trustd decides whether a certificate can be trusted: for every HTTPS connection an app makes, and for the code signatures of apps and updates. It lives at /usr/libexec/trustd. Two copies ran on our Mac, one as the _trustd system user and one as us.
| Reading on our Mac | Value |
|---|---|
| Energy impact during normal work | 1.4 |
| CPU in the same sample | 1.4% |
| Memory | 6 to 9 MB |
Why is trustd using CPU?
- A browser or app opening many secure connections at once.
- Launching many apps, or a developer tool running many signed binaries.
- Checking whether certificates have been revoked, which needs the network; on a slow or filtered network those checks wait and retry.
Short spikes are normal. Constant high use usually traces back to one app making connections in a loop, which you can see with nettop; see which app is using the internet.
See it live
Free Mac's System tab ranks every process by processor use and energy impact, once a second, and marks the ones macOS will not let you quit as protected. See also syspolicyd.
Related: syspolicyd high CPU and logd high CPU.
Common questions
What is trustd on a Mac?
The macOS process that checks certificates for secure connections and signed software.
Why are there two trustd processes?
One runs for the system and one for your account. Both are normal.
Why is trustd using CPU?
Many new secure connections or app launches at once, or slow revocation checks on a filtered network.