# Vessel

> Vessel (Kinit Inc.) is a developer-first embedded integrations platform for go-to-market software.
> It gives a product team one contract to read and write a customer's CRM, sales engagement, chat,
> dialer and marketing automation tools, plus a drop-in browser component (Vessel Link) that handles
> the end user's authorization. Three modules sit on top of an open-source integrations library:
> Unification (one normalized schema per vertical), Actions (typed, validated wrappers over a single
> provider's native API), and Managed ETL (Vessel syncs the customer's data into a database you own).

## Status as observed 2026-08-13

This file is generated by API Evangelist from Vessel's own published artifacts. It is not published by
Vessel. Two facts an agent must know before planning any call:

- **The API hosts do not answer.** `https://api.vessel.dev/` times out (DNS resolves to
  `core-api-production.fly.dev`); `api.vessel.land` has no DNS record at all. `https://app.vessel.dev/`,
  the login and signup destination, also does not answer, and `https://docs.vessel.dev/` returns 404.
- **The contracts are still public.** All 20 OpenAPI 3.1.0 definitions below were harvested from
  Vessel's own documentation repository, `https://github.com/vesselapi/all-api-docs`, which is the only
  reachable copy of the developer documentation.

The marketing site (`https://www.vessel.dev/`), pricing page and privacy policy remain live.

## Authentication

- Project API token in the `x-vessel-api-token` header on the v2 surface (`api.vessel.dev`); the same
  token goes in `vessel-api-token` — no `x-` prefix — on the legacy v1 surface (`api.vessel.land`).
- A per-connection `accessToken` in the request body identifies which end-customer account the call
  acts on. It is obtained by minting a session/link token, running the Vessel Link modal, and
  exchanging the returned `publicToken`.
- Tokens are requested by emailing support@vessel.dev. There is no OAuth flow for Vessel's own API.

## Calling conventions

- RPC over POST. Almost every operation, including reads, is a POST to a verb-suffixed path such as
  `/api/unifications/crm/contacts/list`. Do not assume GET means read here.
- Cursor pagination: send `cursor`, read `nextPageCursor`.
- `filters` and `include` travel in the request body. Most filters require synced-cache to be enabled.
- Every unified object carries `$native` with the untranslated source record; `/api/passthrough`
  forwards an arbitrary request to the downstream provider.
- **No idempotency mechanism exists.** A retried create double-writes into the customer's CRM.
- **Some client validation failures return 5xx by design.** Do not blindly retry a Vessel 5xx.

## Contracts

- [Platform API](https://github.com/api-evangelist/vessel/blob/main/openapi/vessel-platform-openapi.yml): connections, integrations catalog, session/access tokens, OAuth apps, passthrough, webhooks (15 operations)
- [CRM Unified API v2](https://github.com/api-evangelist/vessel/blob/main/openapi/vessel-crm-openapi.yml): contacts, deals, accounts, leads, notes, tasks, events, emails, calls, users, lists (69 operations)
- [Sales Engagement Unified API](https://github.com/api-evangelist/vessel/blob/main/openapi/vessel-engagement-openapi.yml): sequences, tasks, calls, emails, mailboxes (20 operations)
- [Chat Unified API](https://github.com/api-evangelist/vessel/blob/main/openapi/vessel-chat-openapi.yml): Slack and Microsoft Teams (4 operations)
- [Dialer Unified API](https://github.com/api-evangelist/vessel/blob/main/openapi/vessel-dialer-openapi.yml): Aircall, Dialpad, RingCentral (9 operations)
- [Marketing Automation Unified API](https://github.com/api-evangelist/vessel/blob/main/openapi/vessel-marketing-automation-openapi.yml): Mailchimp, ActiveCampaign, Customer.io (7 operations)
- [CRM API v1 (legacy)](https://github.com/api-evangelist/vessel/blob/main/openapi/vessel-crm-v1-openapi.yml): the first-generation `/crm/*` surface (93 operations)
- [Engagement API v1 (legacy)](https://github.com/api-evangelist/vessel/blob/main/openapi/vessel-engagement-v1-openapi.yml): the first-generation `/engagement/*` surface (44 operations)

### Actions APIs — typed wrappers over one provider's native API

Salesforce (10), Apollo (23), Outreach (17), Salesloft (14), Aircall (9), Dialpad (9), RingCentral (9),
ActiveCampaign (7), Mailchimp (5), Slack (4), Microsoft Teams (4), monday.com (4). Each is published as
its own OpenAPI 3.1.0 definition under `/api/actions/{provider}` — see
`https://github.com/api-evangelist/vessel/tree/main/openapi`.

## Events

Vessel publishes no AsyncAPI. Webhooks are registered per project (per API key) and fire only for
objects enabled in the synced-cache. Two shapes: `system.sync.initial.complete`, and
`object.{module}.{object}.{created|updated|deleted}` carrying only the affected record's id. Delivery
is signed with `x-vessel-webhook-signature`, a SHA-256 of `apiToken:timestamp:body`. Return 2xx or
Vessel retries up to 3 times. See
[the webhook catalog](https://github.com/api-evangelist/vessel/blob/main/asyncapi/vessel-webhooks.yml).

## Errors

Bespoke JSON envelope `{message, errorCode?, metadata?}` — not RFC 9457. None of the 375 published
operations declares any response other than 200, so the contract describes no failure mode at all. The
error semantics live only in prose; see
[the error catalog](https://github.com/api-evangelist/vessel/blob/main/errors/vessel-error-codes.yml).

## Pricing

Start (free, 5 development connections), Launch (custom price, up to 20 connections, email support),
Custom (custom price, unlimited connections, whitelabeling, Slack support). All tiers advertise
unlimited API calls. https://www.vessel.dev/pricing

## Links

- Website: https://www.vessel.dev/
- Documentation source: https://github.com/vesselapi/all-api-docs
- GitHub organization: https://github.com/vesselapi
- Open-source integrations library (MIT, archived): https://github.com/vesselapi/integrations
- Node SDK: https://www.npmjs.com/package/@vesselapi/sdk (1.0.35, 2023-08-23)
- React Link component: https://www.npmjs.com/package/@vesselapi/react-vessel-link (1.1.8, 2023-03-17)
- Feature requests: https://vesselapi.canny.io/
- Support: support@vessel.dev

---
generated: 2026-08-13
method: generated
source: apis.yml + openapi/ + github.com/vesselapi/all-api-docs
note: Vessel publishes no llms.txt; /llms.txt returned 404 on www.vessel.dev and docs.vessel.dev.