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ERC-20 Approvals, Explained

An ERC-20 approval is permission for a contract to transfer tokens up to a stated amount. It is separate from the swap itself and may remain active afterward.

Key idea

Check the spender and allowance amount, not just the app name shown beside them.

In this guide

  1. 01Read the spender
  2. 02Read the amount
  3. 03Review old permissions

Related workflow

Token Approvals →
01

Read the spender

The important address is the contract receiving permission. Confirm that address from a source you trust before granting access to a valuable token.

02

Read the amount

An exact allowance limits exposure to a specific amount. An unlimited allowance is convenient for repeated use, but it remains a much larger permission until it is changed or revoked.

03

Review old permissions

Allowances can outlive the trade that created them. Periodically review active approvals and revoke permissions for contracts you no longer use or trust.

Concept map · schematic

How a token allowance is used

Authorization and spending happen in separate transactions.

  1. 01

    Owner

    Controls the ERC-20 tokens and grants permission

  2. 02

    Allowance

    Token contract records a spender and maximum value

  3. 03

    Spender

    May transfer tokens within the remaining allowance

Important: An approval is not a swap. A permission can remain after the associated trade.

Live, read-only fieldwork

Read a live token allowance

Ask the token contract how much one spender can transfer from one public account.

Inspect one on-chain ERC-20 allowance

Choose a network and supply public addresses. This is one token–owner–spender relationship, not a wallet-wide approvals audit. No wallet connection or signing required.

Source: existing Hexncoin EVM RPC relay using read-only eth_call. The reading does not detect ERC-721 approvals, permits, or other spender/token pairs. A contract may not implement the standard ERC-20 interface correctly.

These examples read public network or indexer data only. You cannot execute trades, approve permissions, or submit transactions here.

Primary references

Documentation and standards

References added

Official technical references for further verification. A source link is not a guarantee that every earlier editorial sentence has been reverified; provider specifications may also change over time.

Originally published 2026-09-12 · Guide text last updated 2026-09-19 · Reference links and live examples updated 2026-10-24

  • ERC-20 token and allowance specificationEthereum Improvement ProposalsRead source ↗

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