> For the complete documentation index, see [llms.txt](https://docs.unbrowse.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.unbrowse.ai/architecture/backend.md).

# Backend

The backend owns the shared route graph and account ledger. The local runtime owns browsing, site credentials, and direct execution.

## Main API groups

| Group      | Examples                                        |
| ---------- | ----------------------------------------------- |
| Resolution | `POST /v1/resolve`, `POST /v1/search`           |
| Execution  | `POST /v1/execute`, `POST /v1/proxy`            |
| Accounts   | `GET /v1/account/me`, `/keys`, `/credits`       |
| Publishing | skill submission, review, visibility, freshness |
| Operations | health, version, metrics, audit events          |

## Credits

Credits are stored as integer micro-units (`*_uc`) to avoid floating-point accounting. `1_000_000` units equal one USD-denominated credit. The user ledger tracks granted, earned, consumed, and available units. Admission and debit must be atomic and idempotency keys prevent a retried execute from being counted twice.

## Route graph

Published contracts contain reusable request shapes, parameter schemas, provenance, and freshness signals. They do not contain captured response bodies or authentication material. Ranking uses intent similarity plus reliability and freshness evidence; an empty result is returned honestly when no candidate is safe to execute.