Mutations

Purchases one specific sell listing outright, at its asking price, from the account's Steam Wallet. This is the instant-buy path; POST /market/createbuyorder/ is the standing-order path and does not execute against a listing directly.

The amounts are sent by the client and must reconcile: total has to equal subtotal + fee, and all three must match the listing as Steam currently prices it. Read them from the listing row rather than computing them, since the fee split depends on the publisher. A mismatch, a stale price, or a listing bought by someone else in the meantime all fail the same way.

Unusually for the Market, success is reported inside wallet_info rather than at the top level: check wallet_info.success == 1. A failure carries a top-level message.

Returns fill progress for one buy order: whether it is still active, how much of the requested quantity has been purchased, and what remains outstanding.

This is the only way to observe a buy order filling. GET /market/mylistings lists orders but does not break down partial fills.

Creates an account buy order. Application failures still use HTTP 200; success: 25 indicates a rejected order and includes message.

Cancels an account buy order. A successful result is {"success":1}.

Creates a sell listing for an owned asset. A successful response can still require mobile or email confirmation.

Removes an account sell listing. Success returns an empty JSON array.