FIXSIM

io.github.GammaThreeTrading/fixsimVersion 0.1.2

Test FIX from Claude, ChatGPT, or Cursor: free sandbox FIX sessions or your own FIXSIM instances.

Status

Responds347 msNov 14, 2026, 14:37 UTCAnswered our handshake without sign-in.

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Last checked: Nov 14, 2026, 14:37 UTC
Latency: 347 ms
Remotes responding: 1 of 1
Sign-in: No sign-in
Hosting: Hosted outside the EU (detected)
Registry data as of: Nov 14, 2026, 21:12 UTC

Data from the official MCP Registry, checked by run.zero. How we check

Connect

Streamable HTTP

https://mcp.fixsim.com/mcpResponds347 msNov 14, 2026, 14:37 UTC

No sign-in

Claude Code

claude mcp add --transport http fixsim https://mcp.fixsim.com/mcp

Claude Desktop and claude.ai

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Settings > Connectors > Add custom connector
Name: fixsim
Remote MCP server URL: https://mcp.fixsim.com/mcp

Cursor

{
  "mcpServers": {
    "fixsim": {
      "url": "https://mcp.fixsim.com/mcp"
    }
  }
}

VS Code

code --add-mcp '{"name":"fixsim","type":"http","url":"https://mcp.fixsim.com/mcp"}'

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Tools

21 tools

Tools of FIXSIM
	Description		Read-only	Idempotent	Open world
`fixsim_act_on_orders`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.	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.	No	Not declared	Not declared	Not declared
`fixsim_cancel_order_out`Have FIXSIM send an Order Cancel Request (35=F) for an order it previously sent out with fixsim_send_order.	Have FIXSIM send an Order Cancel Request (35=F) for an order it previously sent out with fixsim_send_order.	No	Not declared	Not declared	Not declared
`fixsim_get_order_in`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.	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.	Not declared	Yes	Yes	Not declared
`fixsim_get_session`Get one FIX session's settings and live state (logged in?, sequence numbers, connection details).	Get one FIX session's settings and live state (logged in?, sequence numbers, connection details).	Not declared	Yes	Yes	Not declared
`fixsim_list_executions_in`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).	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).	Not declared	Yes	Yes	Not declared
`fixsim_list_executions_out`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.	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.	Not declared	Yes	Yes	Not declared
`fixsim_list_instances`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.	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.	Not declared	Yes	Yes	Not declared
`fixsim_list_orders_in`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.	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.	Not declared	Yes	Yes	Not declared
`fixsim_list_orders_out`Orders FIXSIM sent OUT on a session (created with fixsim_send_order). Pass clOrdId to fetch one.	Orders FIXSIM sent OUT on a session (created with fixsim_send_order). Pass clOrdId to fetch one.	Not declared	Yes	Yes	Not declared
`fixsim_list_securities`Securities (symbol, last price, CUSIP, ISIN) configured on an instance. FIXSIM prices fills from these.	Securities (symbol, last price, CUSIP, ISIN) configured on an instance. FIXSIM prices fills from these.	Not declared	Yes	Yes	Not declared
`fixsim_list_sessions`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.	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.	Not declared	Yes	Yes	Not declared
`fixsim_send_order`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.	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.	No	Not declared	Not declared	Not declared
`fixsim_send_raw_fix`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.	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.	No	Not declared	Not declared	Not declared
`sandbox_act_on_order`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.	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.	No	Not declared	Not declared	Not declared
`sandbox_create_session`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.	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.	No	Not declared	Not declared	Not declared
`sandbox_end_session`End a sandbox session now instead of waiting for it to expire. Frees the slot for the user's IP.	End a sandbox session now instead of waiting for it to expire. Frees the slot for the user's IP.	Yes	Not declared	Not declared	Not declared
`sandbox_get_messages`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.	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.	Not declared	Yes	Yes	Not declared
`sandbox_get_orders`Working orders the user's engine has sent into the sandbox session: ClOrdID, symbol, side, qty, filled, leaves, price, status.	Working orders the user's engine has sent into the sandbox session: ClOrdID, symbol, side, qty, filled, leaves, price, status.	Not declared	Yes	Yes	Not declared
`sandbox_get_session`Re-fetch a sandbox session's connection card by id, including whether auto-fill is on and when it expires.	Re-fetch a sandbox session's connection card by id, including whether auto-fill is on and when it expires.	Not declared	Yes	Yes	Not declared
`sandbox_get_status`Is the user's FIX engine connected to the sandbox session? Returns state: connected, waiting (nobody logged on yet), disabled, or unknown.	Is the user's FIX engine connected to the sandbox session? Returns state: connected, waiting (nobody logged on yet), disabled, or unknown.	Not declared	Yes	Yes	Not declared
`sandbox_set_autofill`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.	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.	No	Not declared	Not declared	Not declared

Details

Registry status: Active
Published: Sep 13, 2026
Updated: Sep 13, 2026
Website: https://www.fixsim.com/sandbox⁠ (opens in a new tab)
Repository: https://github.com/GammaThreeTrading/fixsim-mcp⁠ (opens in a new tab)
Categories (suggested): Communication SecuritySuggested categories are assigned automatically from the registry text and may be wrong. Verified operators can correct them.
GDPR: Not declared

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