github.com/open-frames/standard/blob/v0.0.1/README.md # Open Frames Spec [Draft v0.0.1] Since the launch of [Farcaster Frames](docs.farcaster.xyz/reference/frames/spec), we’ve seen a number of protocols work to add Frames support independently. The original Frames spec was designed for Farcaster and wasn’t set up to handle interactions from different types of applications with unique capabilities. Open Frames is a lightweight extension to the Frames spec to help coordinate the many new applications and protocols adopting Frames. Open Frames is an initiative with the following goals: 1. Allow Frames developers to support interactions from different types of clients 2. Don’t screw up the best thing about Frames: how easy it is to build on We expect the Open Frames specification to evolve, both through improvements to the Farcaster Specification and through the needs of Open Frames applications with different capabilities. ## Actors ### Client Application Client applications are responsible for rendering Frames for end-users, handling interactions with buttons on Frames, and creating the POST payload to be sent to the Frames Server. Client applications must support one or more `clientProtocols`. ### Frames Server A Frames Server is responsible for generating the initial Frames HTML, handling `POST` requests from Client Applications, and storing any state that might be required for the functioning of the Frame. ## Frames Metadata To turn your web pages into Frames, you need to add basic metadata to your page. ### Required Properties | Property | Description | | --- | --- | | `of:version` | The version label of the Open Frames spec. Currently the only supported version is `vNext` | | `of:accepts:$protocol_identifier` | The minimum client protocol version accepted for the given protocol identifier. For example `vNext` , or `1.5`. At least one `$protocol_identifier` must be specified. | | `of:image` | An image which should have an aspect ratio of `1.91:1` or `1:1`. | | `og:image` | An image which should have an aspect ratio of `1.91:1`. Fallback for clients that do not support frames. | ### Optional properties | Property | Description | | --- | --- | | `of:button:$idx` | 256 byte string containing the user-visible label for button at index `$idx`. Buttons are 1-indexed. Maximum 4 buttons per Frame. `$idx` values must be rendered in an unbroken sequence. | | `of:button:$idx:action` | Valid options are `post`, `post_redirect`, `mint`, and `link`. Default: `post` | | `of:button:$idx:target` | The target of the action. For post , post_redirect, and link action types the target is expected to be a URL starting with `` or ``. For the mint action type the target must be a [CAIP-10 URL](github.com/ChainAgnostic/CAIPs/blob/main/CAIPs/caip-10.md) | | `of:post_url` | The URL where the POST payload will be sent. Must be valid and start with `` or `` . Maximum 256 bytes. | | `of:input:text` | If this property is present, a text field should be added to the Frame. The contents of this field will be shown to the user as a label on the text field. Maximum 32 bytes. | | `of:image:aspect_ratio` | The aspect ratio of the image specified in the `of:image` field. Allowed values are `1.91:1` and `1:1`. Default: `1.91:1` | | `of:image:alt` | Alt text associated with the image for accessibility | ## Farcaster Compatibility The following properties are directly compatible with the following Farcaster properties as of Feb 21, 2024 | Open Frames Property | Farcaster Property | | --- | --- | | `of:image` | `fc:frame:image` | | `og:image` | `og:image` | | `of:button:$idx` | `fc:frame:button:index` | | `of:button:$idx:action` | `fc:frame:button:$idx:action` | | `of:button:$idx:target` | `fc:frame:button:$idx:target` | | `of:input:text` | `fc:frame:input:text` | | `of:image:aspect_ratio` | `fc:frame:image:aspect_ratio` | | `of:accepts:farcaster` | `fc:frame` | Frames Servers that wish to handle both Farcaster and Open Frames interactions are recommended to include a complete set of both `of:` and `fc:frame` meta tags. If a complete set of Open Frames tags are not present in the page, Client Applications may choose to fall back to equivalent `fc:frame` tags if the `of:accepts:$protocol_identifier` tag is present. ## The Client Protocol Identifier `clientProtocol` is a string identifier for a client’s capabilities that can be used to negotiate compatibility between the Client Application and the Frame Server. Each Frame Server must advertise which `clientProtocol`s it is capable of receiving button clicks from through the `of:accepts:$protocol_identifier` meta tag included in each HTML response. ```html <meta property="of:accepts:xmtp" content="2024-02-01" /> <meta property="of:accepts:lens" content="1.1" /> ``` If a Frame Server declares that it is compatible with a client protocol, Client Applications capable of sending POST responses using that protocol should feel confident that the Frame will work as expected. Client protocol strings must conform to the following format: `$PROTOCOL_IDENTIFIER@$PROTOCOL_VERSION`. Protocol versions are a string, and it is up to each protocol to decide how it should specify versions. For example, a Farcaster client today might define it’s `clientProtocol` as `farcaster@vNext`. The version specified in the `of:accepts:*` tag should be the earliest version of the client protocol with which the Frames Server is compatible. Client applications must check the accepts tag for their protocol and ensure that they are capable of sending POST payloads in a format that the Frame Server can understand. If the `of:accepts:$client_protocol` field is absent, client applications may choose to assume that the Frame Server only accepts requests using the Farcaster request format using the version specified in the `fc:frame` meta tag. If the client application does not support any of the listed client protocols, the client can choose to skip rendering the Frame entirely or show the Frame with the buttons disabled. When sending a POST to the Frame Server, client applications must include the `clientProtocol` used to generate the payload, which will allow the Frame server to know what data is available and how to verify the `trustedData.messageBytes`. ## `POST` Payloads When a user clicks a button on a Frame, the Frame developer receives a `POST` request with a payload containing both `untrustedData` and `trustedData`. The `trustedData.messageBytes` can be verified by Frame developers so that they can provably know that the contents of that payload were signed by a given user. We propose a minimum schema for all `POST` payloads that can be implemented by any Open Frames `clientProtocol`. ```tsx type FramesPost = { clientProtocol: string; // The client protcol used by the client to generate the payload untrustedData: { url: string; // The URL of the Frame that was clicked. May be different from the URL that the data was posted to. unixTimestamp: number; // Unix timestamp in milliseconds buttonIndex: number; // The button that was clicked inputText?: string; // Input text for the Frame's text input, if present. Undefined if no text input field is present }; trustedData: { messageBytes: string; }; }; ``` Different client protocols may choose to include additional fields in the `untrustedData` and `trustedData` portions of the POST payload. Frame Servers may use the `clientProtocol` as a hint for what additional fields are available. All client protocols must include at least the common fields defined above. While the payload is similar to the [Farcaster Frames Spec](docs.farcaster.xyz/reference/frames/spec), it differs in two important ways. The first is the addition of the `clientProtocol` field. The second is that in place of a `timestamp`, which in Farcaster is the number of seconds since the Farcaster epoch, Open Frames uses the `unixTimestamp` field which is the number of seconds since the unix epoch.