Note Actions and Blockchain Links (Blinks)

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Solana Actions are specification-compliant APIs that return transactions on the Solana blockchain to be previewed, signed, and sent across a number of various contexts, including QR codes, buttons + widgets, and websites across the internet. Actions make it simple for developers to integrate the things you can do throughout the Solana ecosystem right into your environment, allowing you to perform blockchain transactions without needing to navigate away to a different app or webpage.

Blockchain links – or blinks – turn any Solana Action into a shareable, metadata-rich link. Blinks allow Action-aware clients (browser extension wallets, bots) to display additional capabilities for the user. On a website, a blink might immediately trigger a transaction preview in a wallet without going to a decentralized app; in Discord, a bot might expand the blink into an interactive set of buttons. This pushes the ability to interact on-chain to any web surface capable of displaying a URL.

Simplified Type Definitions

The types and interfaces declared within this readme files are often the simplified version of the types to aid in readability.

For better type safety and improved developer experience, the @note-protocol/actions-spec package contains more complex type definitions. You can find the source code for them here.

Contributing

If you would like to propose an update the Solana Actions specification, please publish a proposal on the official Solana forum under the Solana Request for Comments (sRFC) section: https://forum.solana.com/c/srfc/6

Specification

The Solana Actions specification consists of key sections that are part of a request/response interaction flow:

• Solana Action URL scheme providing an Action URL
• OPTIONS response to an Action URL to pass CORS requirements
• GET request to an Action URL
• GET response from the server
• POST request to an Action URL
• POST response from the server

Each of these requests are made by the Action client (e.g. wallet app, browser extension, dApp, website, etc) to gather specific metadata for rich user interfaces and to facilitate user input to the Actions API.

Each of the responses are crafted by an application (e.g. website, server backend, etc) and returned to the Action client. Ultimately, providing a signable transaction or message for a wallet to prompt the user to approve, sign, and send to the blockchain.

URL Scheme

A Solana Action URL describes an interactive request for a signable Solana transaction or message using the solana-action protocol.

The request is interactive because the parameters in the URL are used by a client to make a series of standardized HTTP requests to compose a signable transaction or message for the user to sign with their wallet.

solana-action:<link>

• A single link field is required as the pathname. The value must be a conditionally URL-encoded absolute HTTPS URL.

• If the URL contains query parameters, it must be URL-encoded. URL-encoding the value prevents conflicting with any Actions protocol parameters, which may be added via the protocol specification.

• If the URL does not contain query parameters, it should not be URL-encoded. This produces a shorter URL and a less dense QR code.

In either case, clients must URL-decode the value. This has no effect if the value isn't URL-encoded. If the decoded value is not an absolute HTTPS URL, the wallet must reject it as malformed.

OPTIONS response

In order to allow Cross-Origin Resource Sharing (CORS) within Actions clients (including blinks), all Action endpoints should respond to HTTP requests for the OPTIONS method with valid headers that will allow clients to pass CORS checks for all subsequent requests from their same origin domain.

An Actions client may perform "preflight" requests to the Action URL endpoint in order check if the subsequent GET request to the Action URL will pass all CORS checks. These CORS preflight checks are made using the OPTIONS HTTP method and should respond with all required HTTP headers that will allow Action clients (like blinks) to properly make all subsequent requests from their origin domain.

At a minimum, the required HTTP headers include:

• Access-Control-Allow-Origin with a value of *
  • this ensures all Action clients can safely pass CORS checks in order to make all required requests
• Access-Control-Allow-Methods with a value of GET,POST,PUT,OPTIONS
  • ensures all required HTTP request methods are supported for Actions
• Access-Control-Allow-Headers with a minimum value of Content-Type, Authorization, Content-Encoding, Accept-Encoding

For simplicity, developers should consider returning the same response and headers to OPTIONS requests as their GET response.

The actions.json file response must also return valid Cross-Origin headers for GET and OPTIONS requests, specifically the Access-Control-Allow-Origin header value of *.

See actions.json below for more details.

GET Request

The Action client (e.g. wallet, browser extension, etc) should make an HTTP GET JSON request to the Action's URL endpoint.

• The request should not identify the wallet or the user.
• The client should make the request with an Accept-Encoding header.
• The client should display the domain of the URL as the request is being made.

GET Response

The Action's URL endpoint (e.g. application or server backend) should respond with an HTTP OK JSON response (with a valid payload in the body) or an appropriate HTTP error.

• The client must handle HTTP client errors, server errors, and redirect responses.

• The endpoint should respond with a Content-Encoding header for HTTP compression.

• The endpoint should respond with a Content-Type header of application/json.

• The client should not cache the response except as instructed by HTTP caching response headers.

• The client should display the title and render the icon image to user.

GET Response Body

A GET response with an HTTP OK JSON response should include a body payload that follows the interface specification:

export interface ActionGetResponse {
  /** image url that represents the source of the action request */
  icon: string;
  /** describes the source of the action request */
  title: string;
  /** brief summary of the action to be performed */
  description: string;
  /** button text rendered to the user */
  label: string;
  /** UI state for the button being rendered to the user */
  disabled?: boolean;
  links?: {
    /** list of related Actions a user could perform */
    actions: LinkedAction[];
  };
  /** non-fatal error message to be displayed to the user */
  error?: ActionError;
}

• icon - The value must be an absolute HTTP or HTTPS URL of an icon image. The file must be an SVG, PNG, or WebP image, or the client/wallet must reject it as malformed.

• title - The value must be a UTF-8 string that represents the source of the action request. For example, this might be the name of a brand, store, application, or person making the request.

• description - The value must be a UTF-8 string that provides information on the action. The description should be displayed to the user.

• label - The value must be a UTF-8 string that will be rendered on a button for the user to click. All labels should not exceed 5 word phrases and should start with a verb to solidify the action you want the user to take. For example, "Mint NFT", "Vote Yes", or "Stake 1 SOL".

• disabled - The value must be boolean to represent the disabled state of the rendered button (which displays the label string). If no value is provided, disabled should default to false (i.e. enabled by default). For example, if the action endpoint is for a governance vote that has closed, set disabled=true and the label could be "Vote Closed".

• error - An optional error indication for non-fatal errors. If present, the client should display it to the user. If set, it should not prevent the client from interpreting the action or displaying it to the user. For example, the error can be used together with disabled to display a reason like business constraints, authorization, the state, or an error of external resource.

export interface ActionError {
  /** non-fatal error message to be displayed to the user */
  message: string;
}

• links.actions - An optional array of related actions for the endpoint. Users should be displayed UI for each of the listed actions and expected to only perform one. For example, a governance vote action endpoint may return three options for the user: "Vote Yes", "Vote No", and "Abstain from Vote".

  • If no links.actions is provided, the client should render a single button using the root label string and make the POST request to the same action URL endpoint as the initial GET request.

  • If any links.actions are provided, the client should only render buttons and input fields based on the items listed in the links.actions field. The client should not render a button for the contents of the root label.

export interface LinkedAction {
  /** URL endpoint for an action */
  href: string;
  /** button text rendered to the user */
  label: string;
  /**
   * Parameters to accept user input within an action
   * @see {ActionParameter}
   * @see {ActionParameterSelectable}
   */
  parameters?: Array<TypedActionParameter>;
}

The ActionParameter allows declaring what input the Action API is requesting from the user:

/**
 * Parameter to accept user input within an action
 * note: for ease of reading, this is a simplified type of the actual
 */
export interface ActionParameter {
  /** input field type */
  type?: ActionParameterType;
  /** parameter name in url */
  name: string;
  /** placeholder text for the user input field */
  label?: string;
  /** declare if this field is required (defaults to `false`) */
  required?: boolean;
  /** regular expression pattern to validate user input client side */
  pattern?: string;
  /** human-readable description of the `type` and/or `pattern`, represents a caption and error, if value doesn't match */
  patternDescription?: string;
  /** the minimum value allowed based on the `type` */
  min?: string | number;
  /** the maximum value allowed based on the `type` */
  max?: string | number;
}

The pattern should be a string equivalent of a valid regular expression. This regular expression pattern should by used by blink-clients to validate user input before before making the POST request. If the pattern is not a valid regular expression, it should be ignored by clients.

The patternDescription is a human readable description of the expected input requests from the user. If pattern is provided, the patternDescription is required to be provided.

The min and max values allows the input to set a lower and/or upper bounds of the input requested from the user (i.e. min/max number and or min/max character length), and should be used for client side validation. For input types of date or datetime-local, these values should be a string dates. For other string based input types, the values should be numbers representing their min/max character length.

If the user input value is not considered valid per the pattern, the user should receive a client side error message indicating the input field is not valid and displayed the patternDescription string.

The type field allows the Action API to declare more specific user input fields, providing better client side validation and improving the user experience. In many cases, this type will resemble the standard HTML input element.

The ActionParameterType can be simplified to the following type:

/**
 * Input field type to present to the user
 * @default `text`
 */
export type ActionParameterType =
  | "text"
  | "email"
  | "url"
  | "number"
  | "date"
  | "datetime-local"
  | "checkbox"
  | "radio"
  | "textarea"
  | "select";

Each of the type values should normally result in a user input field that resembles a standard HTML input element of the corresponding type (i.e. <input type="email" />) to provide better client side validation and user experience:

• text - equivalent of HTML “text” input element
• email - equivalent of HTML “email” input element
• url - equivalent of HTML “url” input element
• number - equivalent of HTML “number” input element
• date - equivalent of HTML “date” input element
• datetime-local - equivalent of HTML “datetime-local” input element
• checkbox - equivalent to a grouping of standard HTML “checkbox” input elements. The Action API should return options as detailed below. The user should be able to select multiple of the provided checkbox options.
• radio - equivalent to a grouping of standard HTML “radio” input elements. The Action API should return options as detailed below. The user should be able to select only one of the provided radio options.
• Other HTML input type equivalents not specified above (hidden, button, submit, file, etc) are not supported at this time.

In addition to the elements resembling HTML input types above, the following user input elements are also supported:

• textarea - equivalent of HTML textarea element. Allowing the user provide multi-line input.
• select - equivalent of HTML select element, allowing the user to experience a “dropdown” style field. The Action API should return options as detailed below.

When type is set as select, checkbox, or radio then the Action API should include an array of options that each provide a label and value at a minimum. Each option may also have a selected value to inform the blink-client which of the options should be selected by default for the user (see checkbox and radio for differences).

This ActionParameterSelectable can be simplified to the following type definition:

/**
 * note: for ease of reading, this is a simplified type of the actual
 */
interface ActionParameterSelectable extends ActionParameter {
  options: Array<{
    /** displayed UI label of this selectable option */
    label: string;
    /** value of this selectable option */
    value: string;
    /** whether or not this option should be selected by default */
    selected?: boolean;
  }>;
}

If no type is set or an unknown/unsupported value is set, blink-client should default to text and render a simple text input.

The Action API is still responsible to validate and sanitize all data from the user input parameters, enforcing any “required” user input as necessary.

For platforms other that HTML/web based ones (like native mobile), the equivalent native user input component should be used to achieve the equivalent experience and client side validation as the HTML/web input types described above.

POST Request

The client must make an HTTP POST JSON request to the action URL with a body payload of:

{
  "account": "<account>"
}

• account - The value must be the base58-encoded public key of an account that may sign the transaction.

The client should make the request with an Accept-Encoding header and the application may respond with a Content-Encoding header for HTTP compression.

The client should display the domain of the action URL as the request is being made. If a GET request was made, the client should also display the title and render the icon image from that GET response.

POST Response

The Action's POST endpoint should respond with an HTTP OK JSON response (with a valid payload in the body) or an appropriate HTTP error.

• The client must handle HTTP client errors, server errors, and redirect responses.
• The endpoint should respond with a Content-Type header of application/json.

POST Response Body

A POST response with an HTTP OK JSON response should include a body payload of:

export interface ActionPostResponse {
  /** base64 encoded serialized transaction */
  transaction: string;
  /** describes the nature of the transaction */
  message?: string;
}

• transaction - The value must be a base64-encoded serialized transaction. The client must base64-decode the transaction and deserialize it.

• message - The value must be a UTF-8 string that describes the nature of the transaction included in the response. The client should display this value to the user. For example, this might be the name of an item being purchased, a discount applied to a purchase, or a thank you note.

• The client and application should allow additional fields in the request body and response body, which may be added by future specification updates.

The application may respond with a partially or fully signed transaction. The client and wallet must validate the transaction as untrusted.

POST Response - Transaction

If the transaction signatures are empty or the transaction has NOT been partially signed:

• The client must ignore the feePayer in the transaction and set the feePayer to the account in the request.
• The client must ignore the recentBlockhash in the transaction and set the recentBlockhash to the latest blockhash.
• The client must serialize and deserialize the transaction before signing it. This ensures consistent ordering of the account keys, as a workaround for this issue.

If the transaction has been partially signed:

• The client must NOT alter the feePayer or recentBlockhash as this would invalidate any existing signatures.
• The client must verify existing signatures, and if any are invalid, the client must reject the transaction as malformed.

The client must only sign the transaction with the account in the request, and must do so only if a signature for the account in the request is expected.

If any signature except a signature for the account in the request is expected, the client must reject the transaction as malicious.

actions.json

The purpose of the actions.json file allows an application to instruct clients on what website URLs support Solana Actions and provide a mapping that can be used to perform GET requests to an Actions API server.

The actions.json file response must also return valid Cross-Origin headers for GET and OPTIONS requests, specifically the Access-Control-Allow-Origin header value of *.

See OPTIONS response above for more details.

The actions.json file should be stored and universally accessible at the root of the domain.

For example, if your web application is deployed to my-site.com then the actions.json file should be accessible at https://my-site.com/actions.json. This file should also be Cross-Origin accessible via any browser by having a Access-Control-Allow-Origin header value of *.

Rules

The rules field allows the application to map a set of a website's relative route paths to a set of other paths.

Type: Array of ActionRuleObject.

interface ActionRuleObject {
  /** relative (preferred) or absolute path to perform the rule mapping from */
  pathPattern: string;
  /** relative (preferred) or absolute path that supports Action requests */
  apiPath: string;
}

• pathPattern - A pattern that matches each incoming pathname.

• apiPath - A location destination defined as an absolute pathname or external URL.

Rules - pathPattern

A pattern that matches each incoming pathname. It can be an absolute or relative path and supports the following formats:

• Exact Match: Matches the exact URL path.

  • Example: /exact-path
  • Example: https://website.com/exact-path

• Wildcard Match: Uses wildcards to match any sequence of characters in the URL path. This can match single (using *) or multiple segments (using **). (see Path Matching below).

  • Example: /trade/* will match /trade/123 and /trade/abc, capturing only the first segment after /trade/.
  • Example: /category/*/item/** will match /category/123/item/456 and /category/abc/item/def.
  • Example: /api/actions/trade/*/confirm will match /api/actions/trade/123/confirm.

Rules - apiPath

The destination path for the action request. It can be defined as an absolute pathname or an external URL.

• Example: /api/exact-path
• Example: https://api.example.com/v1/donate/*
• Example: /api/category/*/item/*
• Example: /api/swap/**

Rules - Query Parameters

Query parameters from the original URL are always preserved and appended to the mapped URL.

Rules - Path Matching

The following table outlines the syntax for path matching patterns:

| Operator | Matches | | -------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | * | A single path segment, not including the surrounding path separator / characters. | | ** | Matches zero or more characters, including any path separator / characters between multiple path segments. If other operators are included, the ** operator must be the last operator. | | ? | Unsupported pattern. |

License

The Solana Actions JavaScript SDK is open source and available under the Apache License, Version 2.0. See the LICENSE file for more info.