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How Lead Versions Its APIs

Lead versions per resource, in the URL path. Different resources sit at different versions because they ship and evolve independently — the version prefix tells you which contract you’re on, and nothing else. The current generally available version of every resource, and the next version where one is in progress: Keep using the current GA version until the next version is available. Lead announces migration timelines and sunset dates in Upcoming Changes. Sandbox simulators live under the corresponding version (/v1/simulate/…, /v2/simulate/…, plus /v0/fundings/{id}/advance and /v0/simulate/lending/disbursements/{id}/advance). A lower number does not mean less stable: /v0 resources are production APIs. A resource’s version only increments when Lead must make a breaking change to it — as with Wires V2, which supports Fedwire’s ISO 20022 mandates.

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How We Make Changes

Additive changes are not breaking. Lead may, without a version change: add new API endpoints; add new optional request fields; add new response fields; add new values to enums that are documented as extensible; add new event types; increase documented limits. Build your integration to tolerate unknown response fields and unknown event types. Major breaking changes get a new version, notice, and sandbox time. Removing or renaming fields, changing types or semantics, or removing endpoints happens only in a new resource version. Lead announces it in Upcoming Changes with a migration guide and makes it available in sandbox before you need to move.  Deprecations follow the same lifecycle. When Lead schedules a version for retirement, the timeline appears in Upcoming Changes (Announced → Sandbox Available → Enforcement Soon → Released) and the old version keeps working until the stated enforcement date.  Preview APIs are documented before release. Resources labeled Preview are not yet available in sandbox or production and can change before beta. Use their pages to plan an integration, not to build one. When a Preview resource moves to beta, Lead announces it in Upcoming Changes. It then becomes available to all partners in sandbox, and in production for select programs. Beta APIs are the exception. Resources labeled API — Beta may change without a version increment. Lead announces these changes in advance, and your Technical Account Manager works with you to implement them.