Sponsor TON gas for Telegram Mini Apps

Mini App users often hold USDT and zero TON. Tonkeeper Battery and Telegram Wallet W5 can pay fees in USDT inside those wallets. They cannot top up an address your backend generated, or pay for a write you submit on the user's behalf.

Two kinds of gas sponsorship

Wallet-level gasless: the user is in Tonkeeper / TON Space; fees come from USDT. You do not control that wallet.
Merchant-side sponsorship: your backend calls an API and sends exact TON to a target address. The user may not have a wallet yet.

Telegram requires Mini App Web3 on TON. That constrains the chain, not “users must buy TON first.” Sponsorship is the second sentence.

Pontoon call

bash

curl -X POST https://pontoon.dev/api/v1/sponsor \
  -H "Authorization: Bearer <API-KEY>" \
  -H 'content-type: application/json' \
  -d '{
    "idempotencyKey": "miniapp-user-42",
    "chainKey": "ton",
    "walletAddress": "EQ…",
    "targetAddress": "EQ…",
    "requestedAmount": "20000000",
    "executeNow": true
  }'

requestedAmount is nanotons to send this call, not a fill-to-balance. The same prepaid budget sponsors Tron Energy and BSC. First $10 on-chain unlocks a $3 bonus. Docs: sponsorship API.