1. Choose a pack
A .zip data pack or resource pack, or a folder of Mythic
configs zipped up. You can choose several at once and they are reported
together.
2. How deeply to check
The structural, layout, reference and lint checks always run. The deeper layers need Minecraft's own generated data, which is a few megabytes and is fetched once, then cached by your browser. Whatever you choose, the report states plainly which layers ran and which did not — a check that was skipped is never reported as a pass.
3. Run it
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Report
Passed — badge earned
Issued only for a pack with no errors, no warnings, and every checking
layer actually run. The certificate records a digest of the pack's
contents, so it can be verified later with
python -m mcddd verify.
Same checks, on the command line
This page and the command-line tool run the identical checking core, so they cannot disagree. For CI, use the CLI — it exits non-zero on findings and emits machine-readable JSON.
pip install --no-deps mcddd # no dependencies, by design
python -m mcddd check ./my_pack
python -m mcddd check ./my_pack --format json --require-complete