Authentication
Symmetry I-9 uses two kinds of credentials: a system-level API key for server-to-server calls, and one-time access URIs that authenticate a user into an embedded session. Knowing which to use where is the foundation of every request.Authentication
API keys, embedded access URIs, the API domain, and versioning.
Resources and their state
Every endpoint is scoped to a place in a fixed hierarchy, and an I-9’s progress is tracked as three independent statuses rather than one.Resource Model & Identifiers
How account, employer, employee, and submission nest—and which IDs are UUIDs.
Statuses & Lifecycle
Section 1, countersign, and E-Verify status, and how to track each.
Events: webhooks vs. postback
Symmetry sends you data in two complementary ways:- Webhooks notify your platform in real time when something happens (an employee finishes Section 1, an E-Verify case updates, a document is expiring) so you can act or alert users.
- Postback delivers the completed Form I-9 payload to your employer’s configured URL once the form is done.
Webhooks
Available events, sample payloads, and delivery retries.
Working with API data
Pagination
Page through list endpoints with the
?page query parameter.Timezones
The ten supported timezones, and how to read I-9 dates and timestamps.
Where to go next
Capabilities build on these concepts and are documented in their own sections:Embedded Experiences
Deliver the employee and administrator interfaces in an iframe.
Document Verification
OCR-based screening of identity and work-authorization documents.