Head to head · Payroll run · October 2026 research run
Check vs Salsa
Check scores 67.5 (B) on agent readiness against Salsa's 46.1 (D), and leads in 6 of 7 scored categories. Both do payroll run.
Which one, for what
Check B
Good for A software platform that wants to sell US payroll inside its own product and can sign a partnership, with Check handling tax calculation, money movement and filings.
Ahead on
- Reliability, 80 against 36
- Schema & documentation, 78 against 73
- Agent ergonomics, 83 against 48
- Security & auth, 74 against 56
- Maintenance & community, 72 against 50
- Transparency & trust, 62 against 51
Watch for
No public price and no self-serve signup. The documentation says to request an API key through Check's sales contact
Salsa D
Good for A software platform that wants to sell payroll to its own business customers and can sign a partner agreement, with Salsa handling tax filing and money movement.
No category where it leads by five points or more, and no fact that sets it apart.
Watch for
API tokens come from Salsa after a sales contact. No self-serve signup, public price, free tier or trial was found
Score by category
| Category | Weight this run | Check | Salsa | Edge |
|---|---|---|---|---|
| Reliability | 16%20 | 80 | 36 | Check +44 |
| Performance | 10%pending | pending | pending | not scored in this run |
| Schema & documentation | 13%16.2 | 78 | 73 | Check +5 |
| Agent ergonomics | 13%16.2 | 83 | 48 | Check +35 |
| Security & auth | 14%17.5 | 74 | 56 | Check +18 |
| Payments & pricing | 10%12.5 | 5 | 5 | even |
| Task success | 10%pending | pending | pending | not scored in this run |
| Maintenance & community | 7%8.8 | 72 | 50 | Check +22 |
| Transparency & trust | 7%8.8 | 62 | 51 | Check +11 |
| Negative events | ≤15 | 0 | 0 | |
| Total | 67.5 · B | 46.1 · D |
Facts side by side
| Fact | Check | Salsa |
|---|---|---|
| Kind | HTTP API | HTTP API |
| Vendor | Check Technologies, Inc. | Salsa Software Inc. |
| Hosted endpoint | https://api.checkhq.com | https://api.salsa.dev/api/rest/v1 |
| Transports | HTTP | HTTP |
| Auth | OAuth or key | API key |
| Pricing | Paid | Paid |
| x402 | no | no |
| Licence | Proprietary service under Check's terms of service and partner agreement. The MCP server and CLI on GitHub are MIT | Proprietary service. The website Terms of Use are public and the partner agreement isn't. The browser library @salsa-payroll/salsa-js on npm is MIT |
| Read-only variant documented | yes | no |
| llms.txt | yes | yes |
| Last release | 2026-10-07 | 2026-10-07 |
| Terms last updated | 2021-09-03 | 2022-04-07 |
| Privacy policy last updated | 2024-04-18 | 2025-09-24 |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | yes | yes |
| Terms restrict benchmarking | not found in the text | not found in the text |
| Terms or service can change without notice | not found in the text | yes |
| Arbitration or class-action waiver | not found in the text | yes |
| Popularity | 18 stars | 435 npm/wk |
Verdicts
Check
Graded as embedded payroll through a partner API key, not access to an existing employer's payroll account. The API has idempotency keys on writes, a required preview before approval and queryable request logs. No price is public, a sandbox key comes through Check's sales team, and one API key carries the whole partner account.
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.
Before you call either
Check
- Use https://sandbox.checkhq.com with the sandbox key and https://api.checkhq.com with the production key. A key is not valid across environments
- Preview a payroll before approving it, then pass
preview_started_atto POST /payrolls/{id}/approve so a stale preview fails with 409 - Send
X-Idempotency-Keyon every write. Keys expire after 24 hours, so list the resource before retrying later than that - On 429 wait for
Retry-After. The limit is 10 requests a second in sandbox and for partners paying fewer than 1,000 payees a month, with 100 concurrent requests - Connect the MCP server with
?read_only=trueorX-MCP-Readonly: trueunless writes are intended. In production, approving a payroll moves money
Salsa
- 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
- Call POST /payroll-runs/preview before creating a run, then confirm the PENDING run in a separate call. Confirming starts the employer debit
- Send your own externalId on every create. A repeat returns a uniqueness error, which is the only duplicate protection
- Make sure externalId values are unique across all employers, since each entity type has one namespace
- Mint a user token with the lowest role and the fewest employerIds the task needs, and keep the partner token on the server
Questions
Which is better for AI agents, Check or Salsa?
Check scores 67.5 (B) on agent readiness against Salsa's 46.1 (D), and leads in 6 of 7 scored categories.
Do Check and Salsa need an API key?
Check takes an API key or an OAuth sign-in. Salsa needs an API key.
Can an agent call Check and Salsa without installing anything?
Yes. Check has a hosted endpoint at https://api.checkhq.com and Salsa at https://api.salsa.dev/api/rest/v1.
Other comparisons with Check or Salsa
Machine-readable
- This page as Markdown
/compare/check-payroll-vs-salsa.md· slim.min.md· JSON.json(or sendAccept: text/markdown) - Each listing in full
/api/v1/tools/check-payroll.json·/api/v1/tools/salsa.json - From a terminal
anchor compare check-payroll salsa(the CLI) - Over MCP
compare_tools {"a": "check-payroll", "b": "salsa"}at/mcp, no key