REST API

Every CKEditor AI call is an HTTP request to one of the endpoint families below. This page lists them, says which one you call, and covers the mechanics they all share: versioning, pagination, limits, and error codes. For the base URL, see SaaS or On-Premises.

For the editor integration, start with the CKEditor 5 AI documentation.

Conversations, Actions, and Reviews are called by the CKEditor 5 AI features. You do not choose between them. The feature the user runs does. Choose Document Processing when there is no editor. CKEditor 5 can call it too, through a gateway, and Using CKEditor AI programmatically shows how.

To run the editor itself on a server and write AI results into collaboration documents as suggestions, see Server-side Editor API.

Every endpoint is documented at ai.cke-cs.com/v1/docs, with its request schema, response schema, and error responses. The same content is available as an OpenAPI JSON file, for import into a tool such as Postman or to hand to a coding assistant:

https://ai.cke-cs.com/v1/doc.json

On on-premises deployments, your instance serves the same documentation at /v1/docs and the JSON file at /v1/doc.json, for example http://localhost:8000/v1/docs. The shorter /docs redirects there.

The URL path of each endpoint contains its version, for example /v1/conversations or /v1.1/conversations/{conversationId}/messages. Endpoints are versioned independently. A breaking change ships as a new version of that endpoint. The old version keeps working, and you can migrate when you are ready.

The models endpoint (GET /v1/models/{compatibilityVersion}) also takes a compatibility version, which identifies the set of models available to your integration. See Models for how compatibility versions work.

List endpoints use cursor pagination: conversations, files, documents, web resources, contexts, context files, prompts, context libraries, and the admin conversations listing. Each response contains nextCursor and previousCursor. To fetch the next page, send nextCursor in the cursor query parameter. Send previousCursor for the previous page. The endpoint documentation has the parameters for each endpoint.

Rate limits apply to requests and tokens per minute. File limits apply to what you attach to a conversation. Each model also has its own context limits.

Rate limits apply to requests that call a model, search the web, or scrape a page. Request limits count requests, and the token limit counts input tokens. Both are enforced per minute, per organization and per user. When you exceed a limit, the API returns a 429 with code rate-limits-exceeded. Wait, then send the request again. The response has no Retry-After header.

The token limit counts input tokens, weighted per model, so the same request consumes a different share of the limit depending on the model. The weights are internal to the service and not returned by the API. Cached tokens count too, except for Anthropic cache reads.

A file attached to a conversation can be 25 MB at most (PDF, DOCX, PNG, JPEG, Markdown, HTML, plain text). You can attach up to 100 files per conversation, 30 MB in total. The PDFs in a conversation must not have more than 100 pages in total.

Anthropic and Agent models limit images to 5 MB. Other file types keep the 25 MB limit.

Each model has its own context length, file size, and file count limits, returned by GET /v1/models/{compatibilityVersion}. See Model information on the Models page for an example response.

Every error response carries statusCode, code, message, and traceId. Some errors also include a data object with details, an explanation, and an action. Example:

{
  "statusCode": 403,
  "code": "missing-permissions",
  "message": "The user is missing permissions",
  "traceId": "8f3c1c2e-...",
  "data": { "missingPermissions": ["ai:conversations:write"] }
}

The endpoint documentation lists every error code.

On SaaS, POST /v1/admin/billing/usage returns the credits your environment consumed over a period, in total and per user. It requires a token with the ai:admin permission. See Usage and billing for examples.

• Authentication covers the JWT bearer token every request carries, and the token endpoint that issues it.
• Streaming protocol defines the Server-Sent Events that carry generated content.
• Permissions lists the scopes a token can carry.
• Models lists the available models, their capabilities, and compatibility versions.