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API and MCP reference

What each endpoint and tool returns, and how to read the dates. Access is in private beta: your key and the service address come by email when your waitlist place opens.

Reading the data

Every value has a date. observed_date is the day we recorded the rate. Cite it.
Recorded or carried forward. A day with no new record repeats the last rate and says carried-forward, with sourceDate. Never present it as recorded. A median or a spread is calculated from several records, not one bank’s quote.
Lenders by id. Lenders are lowercase ids such as cba, westpac, nab and anz. A product id is unique only inside its lender.
Rates in percent. Rates are % p.a.; moves and spreads are in basis points (bps).

A series response (the shape; the values are made up)

{
  "slug": "hl.var.oo.pi",
  "institution": "cba",
  "points": [
    { "date": "2026-10-13", "value": 6.14, "kind": "observed" },
    { "date": "2026-10-14", "value": 6.39, "kind": "observed" },
    { "date": "2026-10-15", "value": 6.39, "kind": "carried-forward",
      "sourceDate": "2026-10-14" }
  ]
}

HTTP endpoints

JSON over HTTPS. Send your key as Authorization: Bearer rs_live_….

GET/v1/changes

Recorded rate changes: lender, product, the old and new rate, the move in basis points and the day it was recorded.

Parameters since (YYYY-MM-DD, default 14 days ago), institution (e.g. cba)

GET/v1/series

Standard series: a lender’s rate for one product type over time, or a spread such as variable minus the cash rate. Each point says recorded or carried forward.

Parameters slugs (from /v1/catalog), institutions, median=1, from, to

GET/v1/catalog

Every series slug and its label, and the history window of each plan.

Parameters none

GET/v1/tiers

The plans: price, history window and rate limit.

Parameters none

POST/v1/ask

A plain-language rates question answered from recorded rows, with no language model. Up to five lines, each with its recorded date.

Parameters body {"question": "…"}

MCP server

MCP is a connection for AI assistants. Add RateSonar to Claude, Cursor or another assistant. JSON-RPC over HTTP.

Client config

{
  "mcpServers": {
    "ratesonar": { "url": "<the address sent with your key>" }
  }
}

toolrate_history(productId, institutionId?, from?, to?, grid?)

One product’s advertised rate over time. grid:true adds one point per day: recorded, or carried forward with the day it repeats.

toolrate_details(institutionId, productId, asOf?)

Every rate tier and condition of one product: fees, features, eligibility, constraints and where each came from.

toolcompare_rates(category, asOf?)

Lenders ranked for one product type: home_loan, savings, term_deposit, business_loan, personal_loan, car_loan or credit_card.

toolrate_changes(institutionId?, sinceDays?)

The change feed: rate moves with basis-point deltas, and products added.

toolseries(slugs, institutions?, median?, from?, to?)

The same standard series as /v1/series, for charts and analysis inside the tool.

Keys and limits

One key per person or app. Create and revoke keys in Analyse once your access opens.
Your plan sets the history window and the rate limit. Free 60 requests a minute, Enthusiast 300, Pro 1,200. Over the limit you get 429 with retry-after.
Errors are JSON. {"error": "…"} with a 4xx or 5xx status.

Get access

Private beta. Join the waitlist and we’ll email you a key.

Join the waitlist