Conventions - Mithril

Base URL

https://api.trymithril.com

All endpoints live under /v1. Requests and responses are JSON with snake_case fields.

Resource IDs

Every resource has a prefixed, opaque string ID. The prefix tells you the type:

Prefix	Resource
`ws_`	Workspace
`sub_`	Subaccount
`key_`	API key
`mkt_`	Market (unified across venues)
`ord_`	Order
`fill_`	Fill
`pos_`	Position

The mkt_ identifier is venue-agnostic: the same market ID maps the same event across Kalshi and Polymarket, so search, quote, and trade need no per-exchange plumbing. To trade a specific outcome you also pass a token_id, which you read from the market’s orderbook.

Units

Prices and quantities are passed as strings, not numbers, to avoid floating-point precision loss on money.

Price — a probability in the range (0, 1]. "0.40" means 40¢ / 40% implied probability. Mithril normalizes venue conventions (Kalshi cents, Polymarket 0–1) to this single scale.
Quantity — a decimal number of shares/contracts, e.g. "5" or "12.5".
Action — "buy" or "sell".
Side — the outcome, "yes" or "no".

Pagination

List endpoints return a cursor envelope:

{
  "data": [ /* ...items... */ ],
  "next_cursor": "eyJ...",
  "has_more": true
}

Pass ?cursor= to fetch the next page and ?limit= to set page size (default 50, max 200). When has_more is false, you’ve reached the end.

curl "https://api.trymithril.com/v1/fills?limit=100&cursor=eyJ..." \
  -H "Authorization: Bearer $MITHRIL_API_KEY"

Timestamps

All timestamps are RFC 3339 / ISO 8601 in UTC, e.g. 2026-07-16T14:30:00Z.

​Base URL

​Resource IDs

​Units

​Pagination

​Timestamps

Base URL

Resource IDs

Units

Pagination

Timestamps