Read a Solana token's real rules with one RPC call (no SDK)

#solana #javascript #web3 #tutorial

A token page can say anything. The mint account cannot lie. This post shows how to read a Solana token's real rules with one standard RPC call: no SDK, no wallet, no keys. We use it every Monday to re-check one token, and it recently corrected our own documentation.

The one call: getAccountInfo with jsonParsed

Every SPL token has a mint account. Ask any Solana RPC node for it with encoding: "jsonParsed" and the node decodes it for you:

// read-mint.mjs · Node 18+ (built-in fetch) · read-only
const MINT = process.argv[2];
const RPC = process.argv[3] || 'https://api.mainnet-beta.solana.com';

const res = await fetch(RPC, {
  method: 'POST',
  headers: { 'content-type': 'application/json' },
  body: JSON.stringify({
    jsonrpc: '2.0', id: 1, method: 'getAccountInfo',
    params: [MINT, { encoding: 'jsonParsed', commitment: 'finalized' }],
  }),
});
const { result, error } = await res.json();
if (error || !result?.value) throw new Error(JSON.stringify(error ?? 'account not found'));

const v = result.value;
const info = v.data?.parsed?.info ?? {};
const exts = info.extensions ?? [];
const has = name => exts.find(e => e.extension === name);

console.log('slot              ', result.context.slot);
console.log('owner program     ', v.owner);
console.log('account type      ', v.data?.parsed?.type);
console.log('decimals          ', info.decimals);
console.log('mint authority    ', info.mintAuthority ?? 'none (revoked)');
console.log('freeze authority  ', info.freezeAuthority ?? 'none (revoked)');
console.log('extensions        ', exts.map(e => e.extension).join(', ') || 'none');
console.log('transfer fee      ', has('transferFeeConfig') ? JSON.stringify(has('transferFeeConfig').state.newerTransferFee) : 'none');
console.log('transfer hook     ', has('transferHook') ? JSON.stringify(has('transferHook').state) : 'none');
console.log('permanent delegate', has('permanentDelegate') ? JSON.stringify(has('permanentDelegate').state) : 'none');

Run it:

node read-mint.mjs WENWENvqqNya429ubCdR81ZmD69brwQaaBYY6p3LCpk

How to read the answer

Field	What it tells you
`owner program`	`Tokenkeg…` = the original SPL Token program, which cannot carry extensions. `TokenzQd…` = Token-2022, where extensions are possible. Anything else is not a token mint.
`mint authority`	If set, more tokens can be created.
`freeze authority`	If set, a holder's account can be frozen.
`transferFeeConfig`	Token-2022 only: a fee withheld on every transfer, rounded up by the program.
`transferHook`	Token-2022 only: a program that runs on every transfer.
`permanentDelegate`	Token-2022 only: an address that can move or burn tokens from any holder.

None of these is good or bad by itself. A settlement token should have a freeze authority. The point is to know before you hold or integrate.

A real result

Read at finalized slot 468049071 for the WEN mint:

owner program      TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA
account type       mint
decimals           5
mint authority     none (revoked)
freeze authority   none (revoked)
extensions         none
transfer fee       none

The owner is the original SPL Token program, so a transfer fee is not just absent; it is impossible.

This corrected us. Our almanac had said that WEN's January 2024 launch "stress-tested Token-2022". The mint says otherwise: WEN connects to Token-2022 through its history (the poem behind it was minted as an NFT with WNS, a standard built on Token-2022), while the fungible token itself lives on the original program. The launch stress-tested Solana and Jupiter's launchpad. We fixed 23 sentences in the open and kept a public note of what changed.

Make it repeat itself: a weekly GitHub Action

A check you run once is a screenshot. A check that reruns is evidence. Put the script in your repo and add a workflow:

name: Check mint
on:
  workflow_dispatch:
  schedule:
    - cron: "23 5 * * 1"   # every Monday
permissions:
  contents: read
jobs:
  mint:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v5
      - uses: actions/setup-node@v5
        with:
          node-version: 22
      - run: node read-mint.mjs WENWENvqqNya429ubCdR81ZmD69brwQaaBYY6p3LCpk

In our version the script also appends its output to $GITHUB_STEP_SUMMARY, so the result appears on the run page for anyone to see, with the slot it was read at.

Two habits

Read the program before the page. One call tells you whether extensions are even possible.
Re-read on a schedule. Authorities can be revoked or, on some tokens, changed. A dated, rerunnable read beats a claim.

Read-only code. No wallet, no keys. Educational content, not financial advice.

The full script and the weekly job (Apache-2.0):
https://github.com/wen-watt/wen-watt.github.io/blob/main/tools/check-wen-mint.mjs

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