Bullhorn vs Zoho Recruit

Bullhorn

The REST API covers 91 documented entities with required field selection, Lucene and JPQL queries and an event queue. Access is by support ticket or a paid partner contract, and the API Fair Use Policy bars connecting third-party AI or LLM tools or MCP without Bullhorn's written permission. No OpenAPI file or numeric rate limit was found.

Zoho Recruit

OAuth scopes narrow to one module and one operation, the docs have an llms.txt index with a Markdown page per endpoint, and the Free edition includes 5,000 API credits a day. No OpenAPI description, official SDK, SLA or dated API changelog was found, and the documented token refresh puts the client secret in the URL.

Bullhorn

1. Confirm the customer holds Bullhorn's written permission for AI or LLM access before any call. The API Fair Use Policy forbids it otherwise
2. Call /rest-services/loginInfo?username= first to learn the data centre, then use the returned OAuth and REST URLs and follow any 307 redirect
3. Log in once and reuse BhRestToken until a call returns 401, then use the refresh token. Bullhorn limits login rates and may block frequent logins
4. Send BhRestToken as a header, never in the URL, and always pass fields. fields=* is blocked outside /meta
5. On 429 wait one second and retry. Writes have no idempotency key, so read the record back before repeating a PUT

Zoho Recruit

1. Use the api_domain returned with the token, or the regional host (recruit.zoho.com, recruit.zoho.eu, recruit.zoho.in and others). Tokens from one data centre fail on another
2. Send Authorization: Zoho-oauthtoken <token> and refresh hourly. Put refresh parameters in the POST body, not the URL
3. Pass fields on list calls and page with page and per_page (200 at most) until more_records is false
4. Create through /{module_api_name}/upsert with duplicate_check_fields so a retry updates instead of duplicating
5. Move a candidate with PUT /{module_api_name}/status, not upsert. Pass trigger: [] on writes to skip workflows, approvals and blueprints