API docs

Read-only REST over published impact fee schedules. Base URL https://levy.thrain.ai. All endpoints are GET; responses are JSON.

Auth

Send your key on every request: Authorization: Bearer <key>. Quota rides the response headers (x-quota-day, x-quota-remaining). No key yet? Request one.

Quickstart

curl -H "Authorization: Bearer $KEY" \
  "https://levy.thrain.ai/v1/fees/schedules?state=FL&land_use_class=single_family&unit=per_dwelling_unit&as_of=2026-08-29&limit=5"

Each row carries the jurisdiction (GEOID, name, type, state), the fee as the jurisdiction names it plus its normalised category, the printed land-use label and its class, the unit as printed and normalised, the amount and the exact printed token, the stated effective window, any footnote or extractor note, and source_url + source_page — the .gov document and page the line was read from.

Endpoints

Filters on /v1/fees/schedules

Fields on a fee line

Every field ships on every tier. Amounts are the printed figures; nothing is computed.

schedule_key	Stable id of the line: a hash of jurisdiction, fee, service area, land-use tier, unit and effective date
jurisdiction_geoid	Census GEOID: 5-digit county or 7-digit place
jurisdiction_type	county or place
jurisdiction_name	Census name, e.g. Glendale city
state_code	2-letter state code
levying_entity	Who levies the fee when it is not the jurisdiction itself (a school district, a utility); null otherwise
service_area	As printed; citywide means the whole jurisdiction
fee_category	Normalised category (see the filter above)
fee_name	The fee's printed name
land_use_class	Normalised land-use class (see the filter above)
land_use_label	The land-use tier as printed
unit	Normalised charging unit, e.g. per_dwelling_unit
unit_raw	The unit as printed
amount_kind	collected or max_assessable
basis	flat or formula
amount	The printed dollar figure; null on formula lines
amount_raw	The printed token, e.g. $1,282
effective_start	When the line took effect
effective_end	When a later schedule superseded it; null while in force
footnote_text	The printed footnote attached to the line, if any
notes	Collection notes, e.g. where an effective date was taken from when the body does not print one
source_id	The registry source the line came from
source_url	The document the line was read from
source_page	Page number within that document
fetch_timestamp	When the document was last fetched (UTC)
first_seen_timestamp	When this line first appeared (UTC)
last_seen_timestamp	When this line was last observed (UTC)

The change feed

curl -H "Authorization: Bearer $KEY" \
  "https://levy.thrain.ai/v1/fees/changes?since=2026-08-01&change_type=added&state=FL"

Append-only: every fee line, stamped with the run that first observed it. Watched-market jurisdictions are re-checked daily, so a newly adopted schedule shows up here within a day of detection. Store the newest first_seen_at you have seen and pass it back as since=.

The index

The impact fee on one single-family home, month by month. Per jurisdiction the stack is the in-force per-dwelling-unit fees, citywide, collected, without water, wastewater or power. A jurisdiction is in the panel when its stack covers at least three fee categories. The level is the panel median; the chained index links month to month on the common panel from its base month, so coverage growth moves the level but never the index. Nothing is a figure a jurisdiction did not print; the index sums them and says so.

index_key	Stable id of the (as-of date, scope, scope key) row
as_of_date	Month-end the index is computed for (today, for the current month)
scope	national or state
scope_key	US, or the 2-letter state code
panel_size	Jurisdictions in the panel that month: their in-force stack covers at least panel_min_categories fee categories
median_total	Median total single-family impact fee across the panel, dollars
p25_total	25th percentile of panel totals
p75_total	75th percentile of panel totals
mean_total	Mean of panel totals
common_panel	Jurisdictions present in both this month and the previous one
link_ratio	The common panel's aggregate fee this month over last month
base_date	First month the panel reached 10 jurisdictions; the chained index is 100 there
chained_index	100 at base_date, linked forward by link_ratio; null before the base
chain_gap	Months since the base with no common panel, where the index was carried flat
panel_min_categories	The panel rule in force when the row was built
category_key	Categories view: stable id of the (as-of date, scope, scope key, category) row
fee_category	Categories view: the normalised category
jurisdictions_levying	Categories view: panel jurisdictions with a fee in this category
share_levying	Categories view: jurisdictions_levying / panel_size
median_amount	Categories view: median of the category charge across those jurisdictions
p25_amount	Categories view: 25th percentile
p75_amount	Categories view: 75th percentile
conformed_timestamp	When the row was built (UTC)

Errors