FIXSIM MCP server

• fixsim_act_on_ordersFree

  Respond 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.

• fixsim_cancel_order_outwrite actionFree

  Have FIXSIM send an Order Cancel Request (35=F) for an order it previously sent out with fixsim_send_order.

• fixsim_get_order_inwrite actionFree

  Get 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.

• fixsim_get_sessionFree

  Get one FIX session's settings and live state (logged in?, sequence numbers, connection details).

• fixsim_list_executions_inFree

  Execution 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_list_executions_outFree

  Execution 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_list_instancesFree

  List 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_orders_inwrite actionFree

  Orders 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_orders_outwrite actionFree

  Orders FIXSIM sent OUT on a session (created with fixsim_send_order). Pass clOrdId to fetch one.

• fixsim_list_securitiesFree

  Securities (symbol, last price, CUSIP, ISIN) configured on an instance. FIXSIM prices fills from these.

• fixsim_list_sessionsFree

  List 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_send_orderwrite actionFree

  Have 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_send_raw_fixwrite actionFree

  Send 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.

• sandbox_act_on_orderwrite actionFree

  Play 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.

• sandbox_create_sessionwrite actionFree

  Create 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 every order. Keep the returned id; every other sandbox tool needs it.

• sandbox_end_sessionFree

  End a sandbox session now instead of waiting for it to expire. Frees the slot for the user's IP.

• sandbox_get_messagesFree

  The 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_get_ordersFree

  Working orders the user's engine has sent into the sandbox session: ClOrdID, symbol, side, qty, filled, leaves, price, status.

• sandbox_get_sessionFree

  Re-fetch a sandbox session's connection card by id, including whether auto-fill is on and when it expires.

• sandbox_get_statusFree

  Is the user's FIX engine connected to the sandbox session? Returns state: connected, waiting (nobody logged on yet), disabled, or unknown.

• sandbox_set_autofillFree

  Turn 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.

• –Code scanremote-only server, no package to scann/a
• Live reliabilityremote reachable in 962ms20/20
• Tool poisoning21 tool descriptions checked15/15
• Auth qualityAPI key sent as a header8/15
• Maintenancelast push 7 days ago15/15
• Maintainer identityregistry namespace matches repository owner; GitHub account older than a year9/10

FIXSIM: common questions

Is FIXSIM MCP server safe?

Yes, by our scan: it is graded A (89/100). Read the FIXSIM safety report

How do I install FIXSIM?

It runs remotely at mcp.fixsim.com. Add it to Claude Code, Claude Desktop or Cursor with the snippets above, or call it through the mcp.market gateway without installing anything.

Does FIXSIM need an API key?

Yes. The registry entry asks for x-api-key.

Is FIXSIM maintained?

The last commit was 8 days ago (2026-09-13). The latest release is v0.1.2.

Is FIXSIM up?

100% of our last 6 checks got an answer. We check remote servers about four times a day.