REST API

Base URL: https://mocks.chapar.rest/api/v1. All requests and responses are JSON unless noted otherwise. Errors always look like this:

{ "error": "invalid argument: title is required" }

The full contract is in the OpenAPI spec, which you can import into Chapar.

Todos

Method	Path	Description
`GET`	`/todos`	List todos. Filters: `completed`, `priority`, `q` (text search), `limit` (1-100, default 20), `offset`
`POST`	`/todos`	Create a todo. Returns `201`
`GET`	`/todos/{id}`	Get a todo
`PUT`	`/todos/{id}`	Replace a todo; omitted fields are reset to their defaults
`PATCH`	`/todos/{id}`	Update only the fields you send. `"due_at": null` clears the due date
`DELETE`	`/todos/{id}`	Delete a todo. Returns `204`
`POST`	`/todos/reset`	Restore the session’s sample todos

All todo endpoints accept the optional X-Session-Id header. See Sessions.

A todo looks like this:

{
  "id": "0252e97f-54e3-4a1c-a514-77b63b2456c6",
  "title": "Try Chapar",
  "description": "Send a request to the mock server from Chapar.",
  "completed": false,
  "priority": "high",
  "tags": ["chapar", "getting-started"],
  "due_at": "2030-01-01T09:00:00Z",
  "created_at": "2026-09-22T19:33:58.752091Z",
  "updated_at": "2026-09-22T19:33:58.752091Z"
}

Field	Rules
`title`	Required, 1-200 characters
`description`	Up to 2000 characters
`priority`	`low`, `medium` or `high`; defaults to `medium`
`tags`	Up to 10 tags of 1-32 characters
`due_at`	RFC 3339 date-time, or `null`

Examples

Create a todo:

curl -X POST https://mocks.chapar.rest/api/v1/todos \
  -H 'X-Session-Id: alice' \
  -H 'Content-Type: application/json' \
  -d '{"title": "Buy milk", "priority": "high", "tags": ["home"]}'

List your unfinished high-priority todos:

curl 'https://mocks.chapar.rest/api/v1/todos?completed=false&priority=high' \
  -H 'X-Session-Id: alice'

Mark a todo as done and clear its due date:

curl -X PATCH https://mocks.chapar.rest/api/v1/todos/{id} \
  -H 'X-Session-Id: alice' \
  -H 'Content-Type: application/json' \
  -d '{"completed": true, "due_at": null}'

Utilities

Method	Path	What it does
`GET` `POST` `PUT` `PATCH` `DELETE`	`/echo`	Returns the request as the server received it: method, path, query, headers, body, and the body parsed as JSON when it is JSON
`GET`	`/status/{code}`	Responds with any status code from 200 to 599
`GET`	`/delay/{ms}`	Waits up to 10000 ms, then echoes the request
`GET`	`/auth/basic/{user}/{password}`	`200` when Basic credentials match the path, otherwise `401` with a `WWW-Authenticate` challenge
`GET`	`/auth/bearer`	`200` for any `Authorization: Bearer <token>`, otherwise `401`
`GET`	`/auth/api-key`	`200` for any key in the `X-API-Key` header or `api_key` query parameter, otherwise `401`
`GET`	`/cookies`	Returns the cookies you sent
`GET`	`/cookies/set?name=value`	Sets a cookie for every query parameter
`GET`	`/redirect/{n}`	Redirects `n` times (1-10) with `302`, ending at `/echo`
`POST`	`/upload`	Accepts `multipart/form-data`; returns each file’s name, size, content type and SHA-256, plus the form fields
`POST`	`/form`	Accepts `application/x-www-form-urlencoded`; returns the fields
`GET`	`/stream/{n}`	Streams `n` (1-100) newline-delimited JSON lines, 100 ms apart
`GET`	`/bytes/{n}`	Returns `n` random bytes (up to 100 KiB) as `application/octet-stream`
`GET`	`/formats/{format}`	The same sample document as `json`, `xml`, `html`, `text` or `csv`, with the matching content type

Examples

See exactly what your client sends:

curl -X POST 'https://mocks.chapar.rest/api/v1/echo?page=2' \
  -H 'Content-Type: application/json' \
  -d '{"hello": "world"}'

{
  "method": "POST",
  "url": "/api/v1/echo?page=2",
  "path": "/api/v1/echo",
  "protocol": "HTTP/2.0",
  "host": "mocks.chapar.rest",
  "query": { "page": ["2"] },
  "headers": { "Content-Type": ["application/json"], "...": ["..."] },
  "body": "{\"hello\": \"world\"}",
  "json": { "hello": "world" }
}

Check how your client handles errors and timeouts:

curl -i https://mocks.chapar.rest/api/v1/status/503
curl https://mocks.chapar.rest/api/v1/delay/3000

Test each authentication type:

curl -u alice:secret https://mocks.chapar.rest/api/v1/auth/basic/alice/secret
curl -H 'Authorization: Bearer my-token' https://mocks.chapar.rest/api/v1/auth/bearer
curl -H 'X-API-Key: my-key' https://mocks.chapar.rest/api/v1/auth/api-key

Upload a file:

curl -F '[email protected]' -F 'caption=holiday' https://mocks.chapar.rest/api/v1/upload

gRPC API