Test FIX from Claude, ChatGPT, or Cursor: free sandbox FIX sessions or your own FIXSIM instances.
Scored across 21 tools
Two distinct API families (fixsim_* and sandbox_*) are mostly well-separated, but there is clear overlap between fixsim_act_on_orders and sandbox_act_on_order, and between fixsim_get_order_in / fixsim_list_orders_in and sandbox_get_orders, which could cause misselection.
fixsim_* tools use a consistent verb_noun_in/out pattern, and sandbox_* tools also follow a consistent verb_noun pattern. The only deviation is the naming prefix shift (fixsim_ vs sandbox_) and sandbox_set_autofill versus fixsim_list_* style, but overall conventions are predictable.
21 tools is on the heavy side for a FIX simulator, and the overlap between fixsim_* and sandbox_* families means some tools may be redundant. It is borderline but not clearly excessive.
The surface covers session lifecycle, order send/receive, execution reports, raw FIX, securities, and sandbox management, which is strong for a FIX testing tool. Minor gaps exist in explicit order amend/cancel-replace handling and session start/stop controls.
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.
Inputs: action (required), session (required), clOrdIds (required), instance (required), +3 more.
Have FIXSIM send an Order Cancel Request (35=F) for an order it previously sent out with fixsim_send_order.
Inputs: clOrdId (required), session (required), instance (required), apiKey, +2 more.
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.
Inputs: clOrdId (required), session (required), instance (required), apiKey.
Get one FIX session's settings and live state (logged in?, sequence numbers, connection details).
Inputs: session (required), instance (required), apiKey.
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).
Inputs: session (required), instance (required), limit, apiKey, +1 more.
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.
Inputs: session (required), instance (required), limit, apiKey, +1 more.
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.
Inputs: apiKey.
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.
Inputs: session (required), instance (required), limit, apiKey, +1 more.
Orders FIXSIM sent OUT on a session (created with fixsim_send_order). Pass clOrdId to fetch one.
Inputs: session (required), instance (required), limit, apiKey, +1 more.
Securities (symbol, last price, CUSIP, ISIN) configured on an instance. FIXSIM prices fills from these.
Inputs: instance (required), apiKey.
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.
Inputs: instance (required), apiKey.
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.
Inputs: side (required), symbol (required), clOrdId (required), ordType (required), +6 more.
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.
Inputs: session (required), instance (required), fixMessages (required), apiKey.
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.
Inputs: action (required), clOrdId (required), sessionId (required).
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.
Inputs: fixVersion.
End a sandbox session now instead of waiting for it to expire. Frees the slot for the user's IP.
Inputs: sessionId (required).
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.
Inputs: sessionId (required), afterSeq.
Working orders the user's engine has sent into the sandbox session: ClOrdID, symbol, side, qty, filled, leaves, price, status.
Inputs: sessionId (required).
Re-fetch a sandbox session's connection card by id, including whether auto-fill is on and when it expires.
Inputs: sessionId (required).
Is the user's FIX engine connected to the sandbox session? Returns state: connected, waiting (nobody logged on yet), disabled, or unknown.
Inputs: sessionId (required).
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.
Inputs: enabled (required), sessionId (required).
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
Loading tool schema changelog…
Build, test, monitor & improve AI with Future AGI via Claude, Cursor, Windsurf & more.
Trade Papertrade BTC and ETH perps from Claude, ChatGPT, Codex, Cursor and any MCP client.
Send, receive and track real faxes in the US and Canada from Claude, ChatGPT or Cursor.
Aligned market data for AI agents: crypto, stocks, FX and macro on one clock. Local or hosted.
Add one secure layer between your agents and this server.
