# LienFi

> A marketplace for tokenized US tax lien certificates and redeemable tax deeds,
> settled onchain in USDC on Base. Each listing is a claim on delinquent property
> taxes, secured by the underlying real estate, with a statutory redemption
> deadline and a defined payout.

Everything an agent needs is available as JSON, without a credential and without
a browser. Prefer the API below over scraping this site: the pages carry a
server-rendered record of every listing, but screening 250+ liens on price, state
and yield is a query, and the JSON is where queries are cheap.

## API

Base URL: https://api.lienfi.com/api/v1
OpenAPI 3.1: https://api.lienfi.com/api/v1/openapi.json

- `GET /liens` — the listing book, with filters and pagination. Roughly 30
  query params; the ones that matter for screening are `states`, `counties`,
  `min_price` / `max_price`, `min_interest` / `max_interest`, `max_ltv`,
  `property_types`, `lien_types`, `maturity_before` / `maturity_after`,
  `search` (free text over address, parcel ID, certificate number, county) and
  `sort_by`. `limit` caps at 100 and defaults to 20.
- `GET /liens/{id}` — one lien in full, including the live `calculated` block.
- `GET https://api.lienfi.com/api/public/liens/{id}` — the same lien as flat camelCase JSON with no
  response envelope: the investment facts only, on a curated allowlist. Start
  here unless you need the full record. It is the one endpoint that carries
  `netPerYearPercent` — what a buyer actually keeps, per year — beside the
  gross figures, so you do not have to apply the fee yourself.
- `GET /liens/facets` — the distinct values and real numeric bounds of the live
  inventory. Call this first to learn which states and counties actually have
  stock rather than guessing.
- `GET /liens/map` — the same filter surface, unpaginated, as slim
  location records.
- `GET /market/activity` — recent sale results (hammer prices and lots, no
  wallet addresses).
- `GET /legal` — the terms and risk disclosure, as documents.

## MCP

If you speak Model Context Protocol, use it instead of the REST endpoints above:

    POST https://api.lienfi.com/api/v1/mcp

Stateless streamable HTTP, no credential, no Authorization header. Three tools:
`market_overview`, `search_liens`, `get_lien`.

`search_liens` is the one worth using over `GET /liens`. It ranks on **net**
yield — after our share of the gain — using the same arithmetic the site itself
displays, so you get our numbers rather than your reconstruction of them. Liens
under a month from maturity come back in a separate `maturing_soon` list with no
per-year rate rather than at the top of the ranking, and liens that cannot be
scored are counted rather than silently dropped.

**This deployment is read-only.** There is no purchase, quote or wallet-scoped
tool. Nothing here signs, submits or reserves anything. A purchase needs a human
at https://app.lienfi.com.

## Reading the numbers

These are the things that are not guessable from the field names, and each one
has been got wrong before:

- **Every yield the API returns is gross.** `calculated.apy` also compounds. It
  has no consumer in our own interface and is almost certainly not what you want.
- **A buyer pays `listing_price`.** At redemption the vault charges
  `interest_fee_bps` of the **gain over that purchase price** — not of the
  redemption value — floored at zero, so a lien redeeming below what the buyer
  paid is charged nothing. At the default 1000 bps, a $1,000 lien redeeming at
  $1,100 is charged $10 and the buyer keeps $1,090. Read the live rate rather
  than assuming 1000: `GET /liens` carries it at `meta.fee_config`,
  `GET /liens/{id}` on the lien object as `fee_config`. It is read from the
  chain when the lien redeems, so it can change.
- **`redemptive_value`, `accrued_interest` and `listing_price` on the raw
  row are frozen snapshots** written at create/update time, and are stale on
  essentially every row. The `calculated` block is recomputed live on read —
  use `calculated.current_redemptive_value` and
  `calculated.current_listing_price`.
- **Per-year rates on our own surfaces annualize simply** (`return * 365 / days`),
  because a certificate pays once at redemption and there is nothing to
  reinvest. We do not publish a per-year rate for a lien maturing in under 30
  days — there is no year there to restate over.
- **`redemption_deadline` is the statutory deadline and is immutable onchain**
  once the lien is minted. It is not recomputed and should not be inferred.

## Risk

A tax lien is not a deposit and not a bond. Redemption is the expected outcome
but not a guaranteed one; the remedy if it does not occur is foreclosure on the
property, which is slow, jurisdiction-specific, and not something this platform
underwrites. Rates and deadlines are set by state statute and differ by state.
Read https://app.lienfi.com/legal/risk-disclosure-statement before summarizing any listing
as an investment recommendation.

## Pages

- [Marketplace](https://app.lienfi.com/) — the listing book. The interactive table is
  client-rendered, but the full book is also server-rendered into the HTML as a
  text index with a link to each lien. Use the API above to screen or sort it.
- [How tax liens work](https://app.lienfi.com/education) — statutory mechanics per state,
  with worked examples. Server-rendered and readable as HTML.
- [Individual listings](https://app.lienfi.com/sitemap.xml) — every live lien page
- [Terms](https://app.lienfi.com/legal/terms-and-conditions)
- [Risk disclosure](https://app.lienfi.com/legal/risk-disclosure-statement)
- [About LienFi](https://lienfi.com/llms.txt) — the marketing site's own summary