FIXSIM
Test FIX from Claude, ChatGPT, or Cursor: free sandbox FIX sessions or your own FIXSIM instances.
Connect it
Settings → Connectors → Add custom connector
URL: https://mcp.fixsim.com/mcpSettings → Apps & Connectors → Advanced → Developer mode
Create connector with URL: https://mcp.fixsim.com/mcp{
"mcpServers": {
"fixsim": {
"url": "https://mcp.fixsim.com/mcp",
"headers": {
"x-api-key": "<YOUR_X_API_KEY>"
}
}
}
}claude mcp add --transport http fixsim https://mcp.fixsim.com/mcp --header "x-api-key: <value>"{
"servers": {
"fixsim": {
"type": "http",
"url": "https://mcp.fixsim.com/mcp",
"headers": {
"x-api-key": "<YOUR_X_API_KEY>"
}
}
}
}21 tools, verified live
fixsim_list_orders_outread-onlyOrders FIXSIM sent OUT on a session (created with fixsim_send_order). Pass clOrdId to fetch one.
sandbox_get_statusread-onlyIs the user's FIX engine connected to the sandbox session? Returns state: connected, waiting (nobody logged on yet), disabled, or unknown.
fixsim_send_orderHave FIXSIM send a New Order Single (35=D) OUT on a session to the user's system, so they can test how their system handles inbound orders. Follow up with fixsim_list_orders_out and fixsim_list_executions_in to see what came back.
fixsim_list_orders_inread-onlyOrders the user's trading system sent INTO FIXSIM on a session (FIXSIM is the counterparty). Includes ClOrdID, symbol, side, quantity, remaining quantity, order status and the raw FIX message. Optionally filter by FIX OrdStatus code (tag 39): 0 new, 1 partially filled, 2 filled, 4 canceled, 8 rejected.
fixsim_list_executions_inread-onlyExecution reports the user's system sent INTO FIXSIM on a session (when FIXSIM is the order sender and the user's system is the executing side). Optionally filter by ExecID (tag 17).
fixsim_act_on_ordersRespond to orders the user's system sent into FIXSIM: acknowledge, fully or partially execute, reject, cancel remaining, expire, done-for-day, restate, or accept/reject a pending cancel/replace. FIXSIM emits the matching execution reports on the FIX session. Give one or more ClOrdIDs; for executions supply lastPx and, for a partial, lastQty.
sandbox_set_autofillTurn automatic fills on or off for a sandbox session. On: every order the user sends is filled immediately at the security's last price. Off (default): orders are acknowledged and wait for sandbox_act_on_order.
fixsim_cancel_order_outHave FIXSIM send an Order Cancel Request (35=F) for an order it previously sent out with fixsim_send_order.
fixsim_list_sessionsread-onlyList the FIX sessions on an instance with their FIX version, CompIDs, acceptor/initiator role, host/port, enabled and logged-in state, and sequence numbers.
fixsim_list_executions_outread-onlyExecution reports FIXSIM sent OUT on a session (acks, fills, partial fills, rejects, cancels). Pass clOrdId to see the full execution history of one order: ExecType, OrdStatus, LastPx/LastQty, CumQty, LeavesQty, AvgPx and the raw FIX.
fixsim_get_sessionread-onlyGet one FIX session's settings and live state (logged in?, sequence numbers, connection details).
sandbox_act_on_orderPlay the exchange for one order the user sent in: fill (full execution), partial (partial fill), reject, or cancel (cancel the remaining quantity). FIXSIM sends the matching execution report back to the user's engine.
fixsim_get_order_inread-onlyGet one inbound order by ClOrdID (tag 11), including its raw FIX message and audit trail. Use this to explain why an order was rejected or what state it is in.
sandbox_get_ordersread-onlyWorking orders the user's engine has sent into the sandbox session: ClOrdID, symbol, side, qty, filled, leaves, price, status.
sandbox_get_messagesread-onlyThe FIX message log for a sandbox session, oldest first: logons, heartbeats, orders in, execution reports out, rejects. Each message has seq, timeUtc, inbound (true = user's engine sent it), msgType, raw FIX, and parsed tag/value fields. Pass afterSeq (the last seq you saw) to fetch only new messages. Use this to explain what happened on the wire.
sandbox_create_sessionCreate a free, anonymous FIX test session on the FIXSIM Developer Sandbox. No account or API key needed. Returns the connection card: host, port, the SenderCompID the user must put in tag 49, the TargetCompID for tag 56, BeginString, and the expiry (sessions last 4 hours, cap 100 application messages per day). The user's FIX engine connects as the initiator; FIXSIM is the acceptor and acknowledges
sandbox_end_sessioncan modifyEnd a sandbox session now instead of waiting for it to expire. Frees the slot for the user's IP.
fixsim_send_raw_fixSend one or more raw FIX application messages OUT on a session as given (tag=value pairs separated by | or SOH). FIXSIM supplies the session header fields (BeginString, CompIDs, MsgSeqNum, SendingTime) and the checksum. Use for message types the other tools do not cover.
fixsim_list_instancesread-onlyList the FIXSIM instances your API key can access. An instance is a hosted FIX engine; each holds one or more FIX sessions. Start here to learn the instance names other tools need.
fixsim_list_securitiesread-onlySecurities (symbol, last price, CUSIP, ISIN) configured on an instance. FIXSIM prices fills from these.
sandbox_get_sessionread-onlyRe-fetch a sandbox session's connection card by id, including whether auto-fill is on and when it expires.
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