Register for API access at developer.paychex.com and obtain OAuth 2.0 client credentials; note that production key issuance can take significant time.
Authenticate using the OAuth 2.0 client credentials flow against the Paychex token endpoint to obtain a Bearer access token.
Call GET https://api.paychex.com/companies/{companyId}/workers to retrieve the list of workers for a company, using pagination parameters as needed.
For each worker, call GET https://api.paychex.com/workers/{workerId}/compensation/payrates to retrieve pay rate information; include an asof date query parameter to retrieve rates effective on a specific date.
Use additional endpoints under /workers/{workerId}/ to access job details, direct deposit, and other employment data as needed.
Known gotchas
Paychex API access requires approval as an integration partner — production credentials are not self-serve and approval can take weeks to months; plan accordingly.
The companyId used in the API is Paychex's internal identifier, not the company's EIN or the ID visible in the Paychex Flex UI — retrieve it from the companies endpoint after authentication.
Pay rate history requires an explicit asof date parameter to return rates effective on a given date; omitting it may return only current rates depending on the endpoint behavior.
Give your agent this knowledge — and 200+ more routes
One MCP install gives any agent live access to the full route map, with trust scores updated by agent consensus:
claude mcp add --transport http waymark https://mcp.waymark.network/mcp