> ## Documentation Index > Fetch the complete documentation index at: https://cool.computer/docs/llms.txt > Use this file to discover all available pages before exploring further. # Connect a custom domain > Owner only. Asks for hostname, a subdomain you control such as app.example.com (no apex, no wildcard; an internationalized name in its punycode form), on the computer. Publish the two records of the answer at your DNS provider: the TXT record proves you control the hostname, the CNAME sends its traffic to Cool Computers. Asking again for the computer's hostname answers it as it is; another hostname replaces one still waiting for its TXT record. A computer has one domain, an account at most 10, and at most 3 waiting for their TXT record. ## OpenAPI ````yaml https://www.cool.computer/openapi.json put /api/computers/{id}/domain openapi: 3.1.0 info: title: Cool Computers API version: 1.0.0 description: >- Create and operate reachable computers. Each computer keeps a stable name.cool.computer address, persistent files, and agent-ready command execution. REST requests use UTC-aligned one-minute limits: 600 requests per account identified by a recognized valid account bearer credential, a separate 600-request budget per computer-scoped credential, or 60 requests per source IP otherwise. Read-only GETs answered from API state spend a separate read budget reported as account-read or computer-read, so status polling cannot exhaust the budget that protects work and mutations. To bound authentication-provider traffic, at most 60 first-seen bearer values are checked per source IP in a minute; recognized valid credentials use their account or computer policy. Successful bearer authentication is reused for at most five seconds; transient provider failures are not cached. Revoking a credential through this API (POST /api/auth/logout or DELETE /api/api-keys/{id}) drops that reuse in every serving process, so the revoked credential is refused from the next request on; only if that announcement fails does another process keep admitting it, for at most five seconds. JSON request bodies must be sent with Content-Type: application/json; any other body answers 415 unsupported_media_type. A request that gives a published site its own VM (POST /api/computers/{id}/vm, POST /api/computers/{id}/service/run, or a publish whose cool.json declares run) answers with a Cool-Notice header saying that the site now runs there and cool.json no longer applies; exec, terminals, the port proxy and exposure never give one and answer 409 needs_vm on a site with no VM. Every error is an application/problem+json object whose type links to https://cool.computer/docs/api-reference/errors; a malformed body names the unknown field, the wrong type, or the byte where the JSON breaks. Non-exempt API responses include the structured RateLimit and RateLimit-Policy fields; request admission 429 responses use code api_request_rate_exceeded and also include Retry-After. Health, OpenAPI, webhooks, callbacks, SSE, and WebSocket endpoints are exempt from the REST request budget. Authenticated SSE connection attempts remain subject to the authentication safeguards and can receive the same typed 429 response. servers: - url: https://api.cool.computer description: Canonical API origin security: [] tags: - name: Authentication description: Obtain and manage bearer credentials. - name: Billing description: Inspect and manage the account's no-card trial or Pro plan. - name: Computers description: Create, inspect, and delete resident computers. - name: Execution description: Run commands on a computer. - name: Files description: Read and change a computer's persistent files. - name: Publishing description: >- Publish files to a computer's URL as immutable releases, with no VM. To show something, publish the files; to run something, give the site its own VM with POST /api/computers/{id}/vm or start a service with POST /api/computers/{id}/service/run, then use exec, terminals and services. - name: Services description: >- Manage processes and select the HTTP port exposed at a computer's stable address. - name: Email description: Read and send mail through a computer's inbox. - name: Comments description: >- Comments people leave on a computer's page, unless its owner switched comments off: the owner, the people it is shared with and, when the computer is public, any signed-in person. A comment is content; the owner's agents (Operator, or any agent with the owner's credential) pull the open comments and answer them, and the owner hands chosen comments as a job with POST /api/computers/{id}/comments/ask to Operator, or to the owner's own coding agent while it listens on the site with POST /api/computers/{id}/comments/watch (one listening session per site; it claims the job by pulling it, and Operator takes the job over when it goes quiet). - name: Network description: Control a computer's public visibility and outbound network policy. - name: Sharing description: Invite people to use a computer without granting owner controls. - name: Domains description: >- Serve a computer at a hostname you control, such as app.example.com, beside its own address. - name: Public description: Unauthenticated discovery endpoints. - name: Secrets description: Inspect secret sets and their audit history; values are never returned. - name: Integrations description: Connect, inspect and revoke outside service accounts. - name: GitHub description: Work with repository workspaces using the connected user account. - name: Messaging description: >- Connect Telegram, Slack or WhatsApp so direct messages, and mentions of the Slack app in a channel, become chat turns. - name: Terminals description: Inspect a computer's terminal sessions. - name: Operator description: Read the operator agent's conversations, turns, and events. - name: Feedback description: >- Tell the Cool Computers team what works and what does not, with or without an account. externalDocs: description: Cool Computers agent registration guide url: https://www.cool.computer/auth.md paths: /api/computers/{id}/domain: put: tags: - Domains summary: Connect a custom domain description: >- Owner only. Asks for hostname, a subdomain you control such as app.example.com (no apex, no wildcard; an internationalized name in its punycode form), on the computer. Publish the two records of the answer at your DNS provider: the TXT record proves you control the hostname, the CNAME sends its traffic to Cool Computers. Asking again for the computer's hostname answers it as it is; another hostname replaces one still waiting for its TXT record. A computer has one domain, an account at most 10, and at most 3 waiting for their TXT record. operationId: setComputerDomain parameters: - $ref: '#/components/parameters/ComputerID' requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/ComputerDomainSet' responses: '200': headers: RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimit-Policy' description: The computer's custom domain and the records to publish. content: application/json: schema: $ref: '#/components/schemas/ComputerDomain' '400': headers: RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimit-Policy' description: >- Bad Request. `invalid_hostname`: the hostname is not a subdomain anyone can connect; detail says why. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' '401': $ref: '#/components/responses/Unauthorized' '409': headers: RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimit-Policy' description: >- Conflict. `domain_connected`: the computer has another domain that is claimed; remove it first. `hostname_in_use`: the hostname is connected to a computer. `domain_limit`: the account has 10 domains. `too_many_unverified_domains`: 3 domains wait for their TXT record. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' '429': $ref: '#/components/responses/TooManyRequests' '500': $ref: '#/components/responses/InternalServerError' '503': headers: RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimit-Policy' description: >- Service Unavailable. `artifacts_unavailable` means publishing, and with it custom domains, is not configured on this server. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' default: $ref: '#/components/responses/Problem' security: - bearerAuth: [] components: parameters: ComputerID: name: id in: path required: true description: >- The computer's name, such as agent-atlas, or its id (cmp_…). Every caller may use either, the computer's own runtime token included. schema: type: string minLength: 1 example: agent-atlas schemas: ComputerDomainSet: type: object additionalProperties: false required: - hostname properties: hostname: type: string minLength: 1 maxLength: 253 description: A subdomain you control, such as app.example.com. ComputerDomain: type: object additionalProperties: false required: - hostname - state - records properties: hostname: type: string description: The hostname, lowercase, in its punycode form. state: type: string enum: - challenge - issuing - serving - active - removing detail: type: string description: What the domain waits for, or why it was removed. records: type: array description: >- The DNS records to publish: TXT _cool-challenge. with the challenge value, and the CNAME of the hostname. items: type: object additionalProperties: false required: - type - name - value properties: type: type: string enum: - TXT - CNAME name: type: string value: type: string challenge_expires_at: type: string format: date-time description: >- While the state is challenge: when the request is dropped if the TXT record has not appeared. Problem: type: object additionalProperties: false required: - type - title - status - code - detail properties: type: type: string format: uri description: >- https://cool.computer/docs/api-reference/errors, the page that explains every code. title: type: string status: type: integer minimum: 400 maximum: 599 code: type: string pattern: ^[a-z0-9_]+$ detail: type: string resolution: type: string context: type: object additionalProperties: true suggestions: type: array items: type: string maxItems: 3 description: >- Values to send instead. With name_taken: up to three free names made from the requested one, the first with a random suffix; each was free when the answer was made. headers: RateLimit: description: >- The applied policy name, requests remaining after this request, and whole seconds until the current UTC-aligned window resets. schema: type: string pattern: >- ^"(account|account-read|computer|computer-read|source|comment-board|comment-live)";r=[0-9]+;t=([1-9]|[1-5][0-9]|60)$ examples: - '"account";r=599;t=42' - '"computer-read";r=598;t=42' RateLimit-Policy: description: >- The selected policy name, quota, and window in seconds. Valid account credentials use account or account-read with q=600, computer credentials use computer or computer-read with q=600, unauthenticated or unrecognized requests use source with q=60 for their source IP, a browser session's read of a comment board uses comment-board with q=300 for its source IP, and its handshake of a comment live channel uses comment-live with q=60 for its source IP. schema: type: string pattern: >- ^("(account|account-read|computer|computer-read)";q=600|"source";q=60|"comment-board";q=300|"comment-live";q=60);w=60$ examples: - '"account";q=600;w=60' - '"computer-read";q=600;w=60' Retry-After: description: >- Whole seconds to wait after an api_request_rate_exceeded, comment_rate_exceeded, comment_site_rate_exceeded, comment_live_full or computer_starting response before retrying (up to 3600 for comment_site_rate_exceeded, whose window is an hour). Other 429 problem codes describe separate resource or provider limits and do not inherit this retry value. schema: type: integer minimum: 1 maximum: 3600 examples: - 42 responses: Unauthorized: headers: RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimit-Policy' description: Unauthorized. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' TooManyRequests: headers: RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimit-Policy' Retry-After: $ref: '#/components/headers/Retry-After' description: >- Too Many Requests. If the problem code is api_request_rate_exceeded, wait for Retry-After seconds; other problem codes describe a separate limit. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' InternalServerError: headers: RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimit-Policy' description: Internal Server Error. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' Problem: headers: RateLimit: $ref: '#/components/headers/RateLimit' RateLimit-Policy: $ref: '#/components/headers/RateLimit-Policy' description: >- A machine-readable API error with a stable code and recovery instruction. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' securitySchemes: bearerAuth: type: http scheme: bearer bearerFormat: WorkOS user or agent access token, or Cool Computers API key description: >- A Cool Computers API key, user access token, or claimed agent access token in the Authorization header. Follow https://www.cool.computer/auth.md for agent registration and https://www.cool.computer/authentication.md for direct user credentials. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.