Enter an address and you will see how its RNBW balance changed by day since the token's first day. The series is built from every transfer on Base: a balance is everything received minus everything sent, and nothing else is needed for it.
Quick:
The index stores daily increments for each address, and the balance on any given day is their running sum. That compresses the whole history of 1.2 million transfers into five megabytes, split into 256 shards by the first two characters of the address: the browser downloads exactly one shard of about 19 KB instead of the entire 167 MB feed.
Before publishing, the index is checked against the chain: the balance of the twelve largest addresses, computed from the increments, must match what balanceOf returns from the contract. If it does not match, the index is not rewritten. That check has already paid for itself: a transfer where sender and recipient are the same address does not change the balance, and the first version of the calculation, which applied only one side, was off by 2.5 million RNBW on the treasury.
RNBW only, and Base only. Addresses that never held the token are absent from the index — that is not an error but a lack of history. Dates and days are UTC. Addresses that received and sent the token within the same day are absent from the index: at every day boundary their balance was zero. They make up about half of all addresses — the airdrop, moved on the day it arrived.
Index: /api/balhist/. Source — the token's transfer feed from the block it was deployed.