PayFit vs Salsa

PayFit

A public OpenAPI 3.0 file, llms.txt and scoped keys let a paying customer's agent read payroll outputs and write absences. The API cannot run or approve a payroll, new partner integrations are not being accepted, and no idempotency keys or SDKs were found.

Salsa

Salsa is reached as an embedded-payroll partner, not through an employer's existing payroll account. The REST API has a public OpenAPI 3.1 spec with 123 operations, a payroll preview, a separate confirm step and short-lived user tokens limited by role. Access starts with a sales conversation, and no public price, self-serve sandbox, status page or API changelog was found.

PayFit

1. Have a company admin create the key at app.payfit.com/integrations/hub/api with only the scopes the task needs. The key is shown once
2. POST the key to https://oauth.payfit.com/introspect to get company_id, then call https://partner-api.payfit.com/companies/{companyId}/...
3. Page lists with nextPageToken and maxResults, which defaults to 10 and stops at 50
4. Check before repeating a failed POST. There is no idempotency key, and POST /absences creates an absence that is already validated
5. A collaborator or contract created through the API stays incomplete until an HR admin finishes it in the PayFit app, and a new contract takes 2 to 5 minutes to appear

Salsa

1. Use the sandbox token against https://api.sandbox.salsa.dev and the production token against https://api.salsa.dev. Each environment has its own token
2. Call POST /payroll-runs/preview before creating a run, then confirm the PENDING run in a separate call. Confirming starts the employer debit
3. Send your own externalId on every create. A repeat returns a uniqueness error, which is the only duplicate protection
4. Make sure externalId values are unique across all employers, since each entity type has one namespace
5. Mint a user token with the lowest role and the fewest employerIds the task needs, and keep the partner token on the server