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📣 Read an article about Specification-driven development of REST APIs.

☁️ Deploy your OpenAPI spec to Tinyspec Cloud Beta to generate and host beautiful REST API documentation.


NPM version


Tinyspec offers a lightweight and human-readable alternative to the more verbose OpenAPI/Swagger format. It relies on the strengths of the OpenAPI format without the need to maintain the single large JSON or YAML file or to use some special software, instead allowing you to keep your API endpoints and models in separate and easy to maintain files.

Possible outputs include a full OpenAPI specification in YAML and JSON formats, or the API documentation in HTML format created with the help of the bootprint-openapi.


To use tinyspec, install it globally. Use npm for it:

npm install -g tinyspec

Quick Start and Demo

To generate the API documentation, follow these steps:

  1. Create models.tinyspec, endpoints.tinyspec and header.yaml files. You can find more information on how to write these files yourself below.
  2. Run tinyspec -h.

You documentation is generated! Check out this DEMO to see how it may look like.

Tinyspec Syntax

Tinyspec definition is split into 3 different sections. You specify models and endpoints that the API uses in the special tinyspec format and place any extra information in the header.yaml file.

Models Definition

Models (definitions) are described in models.tinyspec files. You can also split model definitions in multiple *.models.tinyspec files and even place them in folders to make the API specification easier to maintain.

The basic model looks like this:

MyModel {field1, field2}

You can describe any number of models in a single *.models.tinyspec file. Fields should be separated by ,. By default, all fields are required and accept string data values. But if you need a colon in the field name, you should specify the type explicitly.

Data Types

To specify the expected data type, add it after semicolon (:). To make fields accept arrays, add brackets ([]). For example to define an object:

MyModel {field1: b, field2: float[]}

You can use the full type name (string, integer, boolean, etc) or a shorthand (s, i, b and so on). Possible values:

Shorthand Full OpenAPI type OpenAPI format
i integer
s string
b boolean
o object
f float number
(none) date string date
d datetime string date-time
t text string
j json string


You can describe a fixed list of possible values separated by | within parentheses ().

MyModel {color: (sample|42|true)}

References to Other Models

You can reference other models:

Dimensions {width: i, height: i}
Color (red|green|blue)
MyModel {dimensions: Dimensions, color: Color}

Optional Fields

To mark the field as optional, add a question mark (?) after the field name, for example:

MyModel {field1?, field2?: b}

Strict Definition Adherence

By default, objects may contain extra fields that are not specified in the model. If you need a strict adherence to the schema, add an exclamation mark (!) before the definitions, for example:

MyModel !{field1, field2}

This is a representation of OpenAPI additionalProperties: false.

Reusing Previously Defined Model

You can reuse the defined model object and create a new one as needed. Use the less-than sign (<) to reuse the object. When you reuse the object, you can remove a part of its definition. To do this, add a minus sign before the field (-). You can also add additional fields as needed. Here is how you can do this:

MyModel {field1, field2}
MyOtherModel < MyModel {-field2, field3}

As a result, MyOtherModel will have field1 and field3 values, but field2 will be excluded.

Multi-line Models

Your models may be multi-line:

MyModel {
    field2: b

Models Description

To create a description for the model, add a text line prefixed with // before its definition. Description may be multi-line and supports Markdown. Here is how it looks like:

// My _perfect_ tiny model
MyModed {field}

Endpoints (Paths) Definition

Endpoints (paths) are described in endpoints.tinyspec files. As with models definitions, you can split endpoint definitions into multiple *.endpoints.tinyspec files or place them in folders to make the specification easier to maintain.

The basic endpoint definition looks like this:

POST /resources {key: Model}
    => {success: b, error: b}
GET /resources
    => {key: Model[]}

You can expand it in the following ways:

Parameters and Responses

Request body parameters are specified using {...} right after the resource name (see example above).

To specify query parameters, add the question mark (?) after the path and list the query parameters. You can add multiple parameters by connecting them with the ampersand symbol (&).

Responses are specified below the endpoint definitions prefixed with an indent and => sign. You can specify status before the response definition, otherwise the status 200 is used by default. You can also provide a response description using a text line prefixed with //.

Parameters and responses definition format is the same as for models. For example, you can refer to other models, make some parameters optional or specify the required data type:

GET /examples?sort&limit?:i
    => {examples: Example[], totalCount?: i}
    // Response description
    => 404 NotFoundError

Endpoints Description

To create a description for the endpoint, add a text line prefixed with // before its definition. Description may be multi-line and supports Markdown. Here is how it looks like:

// Get **ALL** objects.
GET /examples
    => {examples: Example[]}

Automatic Generation of Basic Methods

You can quickly create CRUDL actions (create, retrieve, update, delete, list) for a specified resources by using a dollar sign ($) followed by actions abbreviation (i.e. $CRUDL) in place of the request method. For example:

$CRUDL /examples

This tiny piece would be an equivalent to:

// **List** _examples_
GET /examples
    => {examples: Example[]}

// **Create** new _example_
POST /examples {example: ExampleNew}
    => 201 {example: Example}

// **Retrieve** _example_
GET /examples/:id
    => {example: Example}

// **Update** _example_
PATCH /examples/:id {example: ExampleUpdate}
    => {example: Example}

// **Delete** _example_
DELETE /examples/:id
    => {success: b}

If you only need some methods, omit the key you do not need (for example $RD will only create retrieve and delete actions).

By default the last path member is used to produce model name and payload keys (see above). Alternatively, you can specify your own key and model name. You can also add postfix $ to the model name to append *New and *Update postfixes in generated endpoints:

$CRUDL /examples {myKey: MyModel$}


If your API uses authorization, describe the authorization method in the headers.yaml file and then address it before the endpoint definition by using the "at" sign (@). For example:

// header.yaml
    name: X-Access-Token
    type: apiKey
    in: header

// examples.endpoints.tinyspec
@auth GET /examples
    => {examples: MyModel}

Endpoint Tags

Tags let you group endpoints by the parameter you need. For example you can group your endpoints by your API client type or role. To create a tag, add it with semicolon (:) before the definition. For example, to create the Admin endpoints group:

    GET /users
        => {users: User[]}

Tags are consistent across all endpoint definition files.

Note: OpenAPI requires unique METHOD /URLs for each endpoint specified. To make endpoints separated by tags unique, add the group name in brackets:

Guest endpoints:
    GET /articles (guest)
        => {articles: Article[]}

Admin endpoints:
    GET /articles (admin)?filter&sort&limit:i
        => {articles: Article[], totalCount: i}

API General Information

For any API information other than API endpoints and models you use the header.yaml file. The file should be written in regular OpenAPI format.


You can add one-line comments prefixed with symbol # in any place. Comments will be ignored during parsing.

Generating Documentation

To generate OpenAPI or HTML specification from tinyspec format, run it with one of the available options:

tinyspec [option]

    --yaml | -y     Generate OpenAPI/Swagger YAML
    --json | -j     Generate OpenAPI/Swagger JSON
    --html | -h     Generate HTML/CSS document
    --src | -s      Path to sources directory, defaults to current directory
    --output | -o   Path to place generated files
    --add-nulls     Include `null` as possible value for non-required fields
    --help          Display this help

Generating Documentation for Existing Projects With Support of GitHub Pages

To generate the documentation for GitHub pages from the existing project:

  • Install tinyspec locally: npm install --save-dev tinyspec.
  • Create your *.tinyspec definitions and header.yaml.
  • Edit package.json to prepare the documentation for GitHub Pages:
  "scripts": {
    "docs": "tinyspec -h -o ../docs/"
  • Execute the npm run docs command, commit and push changes and check out your GitHub static website.

For more information about GitHub Pages, see this article.

Using With Asciidoctor

Check out this repo to produce even more beautiful HTML (and PDF) output.

Tinyspec Cloud

Tinyspec Cloud is a documentation hosting service with a themes marketplace launching soon.

OpenAPI version

The current version of tinyspec produces Swagger/OpenAPI 2.0. The new 3.0 version has got some nice features there, but is not well supported by most third-party tools yet. The compatibility with OpenAPI 3.0 is to be added in future.


Contributions and feedback are always welcome. If you have an idea on how to make tinyspec better, feel free to create an issue and/or pull request.


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