Swagger files can be downloaded from the Vend website  https://docs.vendhq.com/reference.  Goto the specification section for each API. For example
https://docs.vendhq.com/reference/3-beta/spec   Download spec

New dated API OpenAPI files can be found for example at  https://x-series-api.lightspeedhq.com/v2026.01/openapi/api-2026-01.yaml

2026-07 found here  https://x-series-api.lightspeedhq.com/openapi/api-2026-07.yaml