calcom/cal.com: technical due diligence, read from its repository

The median source file here is 37 lines. 26 files exceed 1,000 lines, the largest being 4,769. Size is not a defect on its own — some problems genuinely live in one place — but these are where merge conflicts, review fatigue and single-owner knowledge concentrate, and they are the first thing that slows an inheriting engineer down.

The suite is configured to retry failing tests (packages/platform/examples/base/playwright.config.ts); 1 test is individually marked to retry. A retry turns a flaky test green without saying why it failed, so a green build means the tests passed eventually. Ask how many retries a typical run needs, and which tests need them.

The code is pinned to Node.js 20 (end of life 2026-04-30). None of these receives security fixes any more; the first stopped on 2026-04-30. Moving off an unsupported runtime is rarely a one-line change, so a buyer should ask whether the upgrade is planned and what it touches.

8 files were marked deprecated over two years ago and still are, the oldest since Mar 2022. A deprecation is a promise to remove. Ask what still depends on these, and whether removing them is scheduled.

11 third-party CI actions are referenced by a tag or branch rather than a commit, so they run whatever that tag points to on the day; 1 step pipes a download straight into a shell. Tags have been moved to malicious commits in real supply-chain attacks, and a piped script is whatever the server returns that minute. Pinning to a commit is the fix, and it is small.

75 of 3,815 locked dependencies match 168 published advisories in OSV, 86 of them rated high or critical. A lockfile says which version is installed, not whether the flawed code is reachable from this product, so each needs a look. Most are fixed by an upgrade, and the advisory names the version. This lockfile pins development tools alongside what ships and does not say which is which, so some of these may never reach a user.

13 places set HTML from a value that is neither a literal nor passed through a sanitiser. Where the value can come from a user, that is stored cross-site scripting, and it is the first thing a buyer's security review looks for in a frontend.

The root licence changed 2 time(s). Code taken under earlier terms stays under them; check which terms any fork or customer relied on.

The newest was published on 2026-01-13. A project that publishes advisories is telling its users about its fixes, and the count and pace say how much security work it carries. Whether 1 of them are fixed in the code you ship could not be told from this history: its version is only known to be at least 6.2.0. Answer lives in: the release you run, set against each fixed version. The record is incomplete: NVD: its keyword search for 'cal com' is too broad to read whole (8,357 records).

3 images in the deployment configuration are named without a version or as `latest`. A redeploy can change the software without a commit, a rollback has nothing to roll back to, and nobody can say from the repository what is running.