QR Coin Auction

Participate in QR Coin auctions on Base blockchain. QR Coin lets you bid to display URLs on QR codes — the highest bidder's URL gets encoded when the auction ends.

Contracts (Base Mainnet)

Contract	Address
QR Auction	`0x7309779122069EFa06ef71a45AE0DB55A259A176`
USDC	`0x833589fCD6eDb6E08f4c7c32D4f71b54bdA02913`

How It Works

Each auction runs for a fixed period (~24h)
Bidders submit URLs with USDC (6 decimals — 1 USDC = 1000000 units)
Creating a new bid costs ~11.11 USDC (createBidReserve)
Contributing to an existing bid costs ~1.00 USDC (contributeReserve)
Highest bid wins; winner's URL is encoded in the QR code
Losers get refunded; winners receive QR tokens

Auction Status Queries

Note: The examples below use https://mainnet.base.org (public RPC). You can substitute your own RPC endpoint if preferred.

Get Current Token ID

Always query this first to get the active auction ID before bidding.

curl -s -X POST https://mainnet.base.org \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_call","params":[{"to":"0x7309779122069EFa06ef71a45AE0DB55A259A176","data":"0x7d9f6db5"},"latest"],"id":1}' \
  | jq -r '.result' | xargs printf "%d\n"

Get Auction End Time

# First get the current token ID, then use it here
TOKEN_ID=329  # Replace with result from currentTokenId()
TOKEN_ID_HEX=$(printf '%064x' $TOKEN_ID)

curl -s -X POST https://mainnet.base.org \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_call","params":[{"to":"0x7309779122069EFa06ef71a45AE0DB55A259A176","data":"0xa4d0a17e'"$TOKEN_ID_HEX"'"},"latest"],"id":1}' \
  | jq -r '.result' | xargs printf "%d\n"

Get Reserve Prices

# Create bid reserve (~11.11 USDC)
curl -s -X POST https://mainnet.base.org \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_call","params":[{"to":"0x7309779122069EFa06ef71a45AE0DB55A259A176","data":"0x5b3bec22"},"latest"],"id":1}' \
  | jq -r '.result' | xargs printf "%d\n" | awk '{print $1/1000000 " USDC"}'

# Contribute reserve (~1.00 USDC)
curl -s -X POST https://mainnet.base.org \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_call","params":[{"to":"0x7309779122069EFa06ef71a45AE0DB55A259A176","data":"0xda5a5cf3"},"latest"],"id":1}' \
  | jq -r '.result' | xargs printf "%d\n" | awk '{print $1/1000000 " USDC"}'

Transactions via Bankr

QR Coin auctions require USDC transactions on Base. Use Bankr to execute these — Bankr handles:

Function signature parsing and parameter encoding
Gas estimation
Transaction signing and submission
Confirmation monitoring

Step 1: Approve USDC (One-Time)

Before bidding, approve the auction contract to spend USDC:

Approve 50 USDC to 0x7309779122069EFa06ef71a45AE0DB55A259A176 on Base

Step 2: Create a New Bid

To start a new bid for your URL:

Function: createBid(uint256 tokenId, string url, string name) Contract: 0x7309779122069EFa06ef71a45AE0DB55A259A176 Cost: ~11.11 USDC

Important: Always query currentTokenId() first to get the active auction ID.

Example prompt for Bankr:

Send transaction to 0x7309779122069EFa06ef71a45AE0DB55A259A176 on Base
calling createBid(329, "https://example.com", "MyName")

Step 3: Contribute to Existing Bid

To add funds to an existing URL's bid:

Function: contributeToBid(uint256 tokenId, string url, string name) Contract: 0x7309779122069EFa06ef71a45AE0DB55A259A176 Cost: ~1.00 USDC per contribution

Example prompt for Bankr:

Send transaction to 0x7309779122069EFa06ef71a45AE0DB55A259A176 on Base
calling contributeToBid(329, "https://grokipedia.com/page/debtreliefbot", "MerkleMoltBot")

Function Selectors

Function	Selector	Parameters
`currentTokenId()`	`0x7d9f6db5`	—
`auctionEndTime(uint256)`	`0xa4d0a17e`	tokenId
`createBidReserve()`	`0x5b3bec22`	—
`contributeReserve()`	`0xda5a5cf3`	—
`createBid(uint256,string,string)`	`0xf7842286`	tokenId, url, name
`contributeToBid(uint256,string,string)`	`0x7ce28d02`	tokenId, url, name
`approve(address,uint256)`	`0x095ea7b3`	spender, amount

Error Codes

Error	Meaning	Solution
`RESERVE_PRICE_NOT_MET`	Bid amount below minimum	Check reserve prices
`URL_ALREADY_HAS_BID`	URL already has a bid	Use `contributeToBid` instead
`BID_NOT_FOUND`	URL doesn't have existing bid	Use `createBid` instead
`AUCTION_OVER`	Current auction has ended	Wait for next auction
`AUCTION_NOT_STARTED`	Auction hasn't begun	Wait for auction to start
`INSUFFICIENT_ALLOWANCE`	USDC not approved	Approve USDC first

Typical Workflow

Query currentTokenId() — Get the active auction ID
Check auction status — Verify time remaining
Approve USDC — One-time approval for the auction contract
Decide action:
- New URL: Use createBid (~11.11 USDC)
- Support existing URL: Use contributeToBid (~1.00 USDC)
Monitor — Watch for outbids and contribute more if needed
Claim — Winners receive QR tokens; losers get refunds

Tips

Start small: Contribute to existing bids (~1 USDC) to learn the flow
Check timing: Auctions have fixed end times; plan accordingly
Monitor bids: Others can outbid you; watch the auction
Use Bankr: Let Bankr handle transaction signing and execution
Specify Base: Always include "on Base" when using Bankr

💡 Pro Tip: Contributing to an existing bid is cheaper than creating a new one. Check if someone already bid for your URL before creating a new bid.

qrcoin