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 BaseStep 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
Links
- Platform: https://qrcoin.fun
- Auction Contract: BaseScan
- USDC on Base: BaseScan
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.