Web3 Forms

Web3 Forms let you embed interactive smart contract interfaces directly in your markdown pages. Type a web3:// link, and Simple Page turns it into a working form — with labeled inputs, decimal scaling, and wallet integration — right inside your site.

No JavaScript. No React components. Just a URL in an image tag.

How It Works

Embed a Web3 Form by writing a web3:// URI as a markdown image source. The alt text becomes the form title:

![Title](web3://...)

When a visitor opens your page, Simple Page renders this as an interactive form. Read-only calls return data instantly. Transactions prompt the visitor's wallet for a signature.

Examples

Read Contract State

Read-only calls execute immediately with no wallet required. This example reads a USDC balance:

Markdown:

![USDC Balance](web3://0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48:1/balanceOf/address!0x?returns=(uint256)&labels=(Account)&decimals=(,6))

Result:

The form shows a single input field labeled "Account." Enter any Ethereum address and the result is displayed with 6-decimal scaling (USDC uses 6 decimals).

Send a Transaction

Set mode=tx to create a form that sends a transaction. The visitor's wallet will prompt for a signature.

Markdown:

![Send USDC](web3://0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48:1/transfer/address!0x/uint256!1000000?labels=(Recipient,Amount)&mode=tx&decimals=(,6))

Result:

The form shows two inputs — Recipient (an address) and Amount (scaled to 6 decimals via decimals=(,6)). When the visitor fills them in and clicks the button, their wallet opens to sign a transfer transaction.

Payable Transactions

For functions that accept ETH (marked payable in Solidity), add value and payable=true:

Markdown:

![Wrap ETH](web3://0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2:1/deposit?value=0.01eth&payable=true&mode=tx)

Result:

The form shows a button with 0.01 ETH attached as the call value. Clicking it prompts the visitor's wallet to sign a payable deposit transaction — here, wrapping ETH into WETH.

URI Format

Anatomy of a web3:// URI showing contract, chainId, method, typed arguments, and query parameters. 
web3://<contract>[:chainId]/<method>[/<type>!<value>...]?[query]

Path Segments

Segment Required Description
contract Yes Ethereum address (0x...) or ENS name
chainId No Network ID after a colon (e.g., :1 for mainnet, :11155111 for Sepolia)
method Yes Solidity function name
type!value No Function arguments — each declares its Solidity type and a default value or placeholder

Use type!0x for an empty input field (the visitor fills it in). Use type!<value> for a pre-filled default.

Query Parameters

Parameter Example Description
returns returns=(uint256) Solidity return type for read-only calls. Use returns=() for void. Only used with mode=call
mode mode=tx call (default, read-only) or tx (sends a transaction)
labels labels=(Account,Amount) Human-readable names for each input field. Count must match the number of arguments
value value=0.01eth Adds an ETH value input. Accepts eth suffix or raw wei
payable payable=true Marks the call as payable and shows the value field
decimals decimals=(,6) Scales numeric inputs and the return value. Positional — use commas to skip arguments

Decimals — Positional Scaling

The decimals parameter is a comma-separated list, applied in order:

  1. One entry per function argument
  2. If a return value exists, add one extra entry at the end
  3. Use empty slots for arguments that don't need scaling

Example — two arguments + one return: decimals=(,6,18) means:

  • First argument: no scaling
  • Second argument: divide/multiply by 10^6
  • Return value: divide by 10^18

When to Use Web3 Forms

  • DAO pages — let members interact with governance contracts directly from the docs
  • Token dashboards — show balances, supply, or staking positions
  • Payment forms — accept tips, donations, or payments in ETH/tokens
  • Developer docs — let readers test contract calls without switching to Etherscan