Chinese Text Project vs Free Dictionary

Chinese Text Project's JSON API resolves opaque CTP URNs into full text, titles, and subsection metadata across its library of pre-Qin and Han-era classical Chinese works, and underpins the site's own browser plugins for text lookup and annotation. Anonymous requests work without any key but are rate-limited; logged-in accounts get a higher ceiling, and academic institutions can arrange a subscription that issues API keys for extended, programmatic access.

Free Dictionary API is a keyless REST service built and maintained by a solo developer, returning English word definitions, phonetic spellings, audio pronunciation clips, parts of speech, usage examples, and synonyms/antonyms as plain JSON from a single GET request. It now serves more than 10 million requests a month and is funded entirely through voluntary donations rather than any paid tier.