More complex (sample) XUMM payload JSON

payload.js

{
  custom_meta: {
    instruction: 'Hey! Please sign for:\n\nThis\nand\nthat 🍻',
    blob: {
      myOwnProp: 'Whatever',
      clientCountry: 'Netherlands',
      clientAge: 32
    },
    identifier: 'MY_OWN_UNIQUE_INTERNAL_ID_123'
  },
  options: {
    submit: true,
    multisign: false,
    expire: 500
    return_url: {
      app: 'https://wietse.com/xrpl?payload={id}',
      web: 'https://wietse.com/xrpl?payload={id}'
    }
  },
  user_token: '7ccc19cf-970a-4185-8bd3-49d507bf24ae',
  // txblob: '1200002400000003614000000002FAF0806840000000000000C8732' +
  //   '...' +
  //   '5727D0B4057696574736557696E64E1F1',
  txjson: {
    TransactionType : 'Payment',
    Destination : 'rwiETSee2wMz3SBnAG8hkMsCgvGy9LWbZ1',
    Amount: '1000000',
    LastLedgerSequence: 20,
    Fee: '1337',
    Memos: [
      {
        Memo: {
          MemoData: Buffer.from('Sample XUMM payload', 'utf-8').toString('hex').toUpperCase(),
          MemoFormat: Buffer.from('some/memo', 'utf-8').toString('hex').toUpperCase()
        }
      }
    ]
  }
})

Referenced from the XUMM SDK Readme: https://github.com/XRPL-Labs/XUMM-SDK/blob/master/README.md

A reference for payload options & custom meta can be found in the API Docs.

Instead of providing a txjson transaction, a transaction formatted as HEX blob (string) can be provided in a txblob property.