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Federation

The Stellar federation protocol maps Stellar addresses to an email-like identifier that provides more information about a given user. It’s a way for Stellar client software to resolve email-like addresses such as name*yourdomain.com into account IDs like: GCCVPYFOHY7ZB7557JKENAX62LUAPLMGIWNZJAFV2MITK6T32V37KEJU. Federated addresses provide an easy way for users to share payment details by using a syntax that interoperates across different domains and providers.

Federated addresses​

Stellar federated addresses are divided into two parts separated by the asterisk character (*): the username and the domain. For example: jed*stellar.org:

  • jed is the username
  • stellar.org is the domain

The domain can be any valid RFC 1035 domain name. The username is limited to printable UTF-8 with whitespace and the following characters excluded: <*,>.

Note that the @ symbol is allowed in the username. This means you can use email addresses in the username of a federated address. For example: [email protected]*stellar.org.

Supporting federation​

To support federation, first, create a stellar.toml file, and publish it at https://YOUR_DOMAIN/.well-known/stellar.toml. Complete instructions for doing that can be found in the stellar.toml specification (aka SEP-1).

In general, you will want to include any and all information about your Stellar integration in your stellar.toml. To support federation specifically, you need to add a FEDERATION_SERVER section to your stellar.toml file that tells other people the URL of your federation endpoint.

For example: FEDERATION_SERVER="https://api.yourdomain.com/federation"

Note: your federation server must use https protocol

Once you’ve published the location of your federation server, implement federation url HTTP endpoint that accepts an HTTP GET request and issues responses of the form detailed below:

To make it easier to set up a federation server, you can use the reference implementation designed to be dropped into your existing infrastructure.

Federation requests​

You can use the federation endpoint to look up an account ID if you have a Stellar address. You can also do reverse federation and look up a Stellar address from an account ID or a transaction ID. This is useful to see who has sent you a payment.

Federation requests are http GET requests with the following form:

?q=<string to look up>&type=<name,forward,id,txid>

Supported types:

  • Name Example: https://YOUR_FEDERATION_SERVER/federation?q=jed*stellar.org&type=name
  • Forward Used for forwarding the payment to a different network or different financial institution. The other parameters of the query will vary depending on what kind of institution is the ultimate destination of the payment and what you as the forwarding anchor supports. Your stellar.toml file should specify what parameters you expect in a forward federation request. If you are unable to forward or the other parameters in the request are incorrect you should return an error to this effect. Example request: https://YOUR_FEDERATION_SERVER/federation?type=forward&forward_type=bank_account&swift=BOPBPHMM&acct=2382376
  • Id Not supported by all federation servers. Reverse federation will return the federation record of the Stellar address associated with the given account ID. In some cases, this is ambiguous. For instance, if an anchor sends transactions on behalf of its users, the account id will be of the anchor, and the federation server won’t be able to resolve the particular user that sent the transaction. In cases like that, you may need to use txid instead. Example: https://YOUR_FEDERATION_SERVER/federation?q=GD6WU64OEP5C4LRBH6NK3MHYIA2ADN6K6II6EXPNVUR3ERBXT4AN4ACD&type=id
  • Txid Not supported by all federation servers. Will return the federation record of the sender of the transaction if known by the server. Example: https://YOUR_FEDERATION_SERVER/federation?q=c1b368c00e9852351361e07cc58c54277e7a6366580044ab152b8db9cd8ec52a&type=txid

Federation Response​

The federation server should respond with an appropriate HTTP status code, headers, and a JSON response.

You must enable CORS on the federation server so clients can send requests from other sites. The following HTTP header must be set for all federation server responses.

Access-Control-Allow-Origin: *

When a record has been found, the response should return 200 OK http status code and the following JSON body:

{
  "stellar_address": <username*domain.tld>,
  "account_id": <account_id>,
  "memo_type": <"text", "id" , or "hash"> *optional*
  "memo": <memo to attach to any payment. if "hash" type then will be base64 encoded> *optional*
}

If a redirect is needed, the federation server should return 3xx http status code and immediately redirect the user to the correct URL using the Location header.

When a record has not been found 404 Not Found http status code should be returned. Every other http status code will be considered an error. The body should contain error details:

{
  "detail": "extra details provided by the federation server"
}

Looking up federation provider via a home domain entry​

Accounts may optionally have a home domain specified. This allows an account to programmatically specify the main federation provider for that account.

Caching​

You shouldn’t cache responses from federation servers. Some organizations may generate random IDs to protect their users’ privacy. Those IDs may change over time.