FeeHistory · the dated record of overwrite-in-place gov fees & rates

Boulder, CO — tracked fees & rates

Field	Current	History
Boulder, CO city sales-tax rate	3.86%	since 2026-06-22

How this works. Government bodies publish a fee or rate and overwrite the old number when it changes — almost none keep a public dated history. We snapshot append-only and hash each observation, so we become the record of what a value was on a given date. Day-1 history is thin and we say so — the immediate value is the forward change-alert; the deep dated history compounds as we keep polling.

Diff API · Change alerts · x402 / agents · All jurisdictions

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