Questions worth asking any tool: which signature level it offers, what the evidence report contains and how others can verify it, whether the signer needs an account, what the limits and prices are, and where the data is stored.
HawkOpen’s answers: simple signature only; the signer needs no account; an evidence report with the document’s SHA-256 fingerprint and an Ed25519 signature; monthly limits by plan; the hosting region is not published yet.