Test FIX from Claude, ChatGPT, or Cursor: free sandbox FIX sessions or your own FIXSIM instances.
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Optional. Your FIXSIM API key (portal.fixsim.com, API Keys). Leave blank to use only the free sandbox tools.
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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.
One of: Ack, FullyExecute, PartialExecute, CancelRemaining, DoneForDay, AckCancelOrdReplaceReq, AcceptCancelOrdReplaceReq, RejectCancelOrdReplaceReq, Reject, Delete, Restate, Expire
ClOrdIDs (tag 11) of the inbound orders to act on
Fill price (LastPx) for executions
Fill quantity (LastQty) for a partial execution
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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.
| Argument | Type | Description |
|---|---|---|
| action* | string | One of: Ack, FullyExecute, PartialExecute, CancelRemaining, DoneForDay, AckCancelOrdReplaceReq, AcceptCancelOrdReplaceReq, RejectCancelOrdReplaceReq, Reject, Delete, Restate, Expire |
| apiKey | string | null | |
| lastPx | number | null | Fill price (LastPx) for executions |
| lastQty | number | null | Fill quantity (LastQty) for a partial execution |
| session* | string | |
| clOrdIds* | array | ClOrdIDs (tag 11) of the inbound orders to act on |
| instance* | string |
{
"type": "object",
"required": [
"instance",
"session",
"action",
"clOrdIds"
],
"properties": {
"action": {
"type": "string",
"description": "One of: Ack, FullyExecute, PartialExecute, CancelRemaining, DoneForDay, AckCancelOrdReplaceReq, AcceptCancelOrdReplaceReq, RejectCancelOrdReplaceReq, Reject, Delete, Restate, Expire"
},
"apiKey": {
"type": [
"string",
"null"
],
"default": null
},
"lastPx": {
"type": [
"number",
"null"
],
"default": null,
"description": "Fill price (LastPx) for executions"
},
"lastQty": {
"type": [
"number",
"null"
],
"default": null,
"description": "Fill quantity (LastQty) for a partial execution"
},
"session": {
"type": "string"
},
"clOrdIds": {
"type": "array",
"items": {
"type": "string"
},
"description": "ClOrdIDs (tag 11) of the inbound orders to act on"
},
"instance": {
"type": "string"
}
}
}Have FIXSIM send an Order Cancel Request (35=F) for an order it previously sent out with fixsim_send_order.
| Argument | Type | Description |
|---|---|---|
| apiKey | string | null | |
| clOrdId* | string | ClOrdID of the order to cancel (becomes OrigClOrdID, tag 41) |
| session* | string | |
| instance* | string | |
| newClOrdId | string | null | New ClOrdID for the cancel request (tag 11); generated if omitted |
| additionalTags | array | null |
{
"type": "object",
"required": [
"instance",
"session",
"clOrdId"
],
"properties": {
"apiKey": {
"type": [
"string",
"null"
],
"default": null
},
"clOrdId": {
"type": "string",
"description": "ClOrdID of the order to cancel (becomes OrigClOrdID, tag 41)"
},
"session": {
"type": "string"
},
"instance": {
"type": "string"
},
"newClOrdId": {
"type": [
"string",
"null"
],
"default": null,
"description": "New ClOrdID for the cancel request (tag 11); generated if omitted"
},
"additionalTags": {
"type": [
"array",
"null"
],
"items": {
"type": [
"object",
"null"
],
"required": [
"tag",
"value"
],
"properties": {
"tag": {
"type": "integer"
},
"value": {
"type": [
"string",
"null"
]
}
}
},
"default": null
}
}
}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.
| Argument | Type | Description |
|---|---|---|
| apiKey | string | null | |
| clOrdId* | string | ClOrdID, FIX tag 11 |
| session* | string | |
| instance* | string |
{
"type": "object",
"required": [
"instance",
"session",
"clOrdId"
],
"properties": {
"apiKey": {
"type": [
"string",
"null"
],
"default": null
},
"clOrdId": {
"type": "string",
"description": "ClOrdID, FIX tag 11"
},
"session": {
"type": "string"
},
"instance": {
"type": "string"
}
}
}Get one FIX session's settings and live state (logged in?, sequence numbers, connection details).
| Argument | Type | Description |
|---|---|---|
| apiKey | string | null | |
| session* | string | Session name from fixsim_list_sessions |
| instance* | string |
{
"type": "object",
"required": [
"instance",
"session"
],
"properties": {
"apiKey": {
"type": [
"string",
"null"
],
"default": null
},
"session": {
"type": "string",
"description": "Session name from fixsim_list_sessions"
},
"instance": {
"type": "string"
}
}
}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).
| Argument | Type | Description |
|---|---|---|
| limit | integer | Max rows to return, newest first (default 25, max 200) |
| apiKey | string | null | |
| execId | string | null | Optional ExecID (tag 17) filter |
| session* | string | |
| instance* | string |
{
"type": "object",
"required": [
"instance",
"session"
],
"properties": {
"limit": {
"type": "integer",
"default": 25,
"description": "Max rows to return, newest first (default 25, max 200)"
},
"apiKey": {
"type": [
"string",
"null"
],
"default": null
},
"execId": {
"type": [
"string",
"null"
],
"default": null,
"description": "Optional ExecID (tag 17) filter"
},
"session": {
"type": "string"
},
"instance": {
"type": "string"
}
}
}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.
| Argument | Type | Description |
|---|---|---|
| limit | integer | Max rows to return, newest first (default 25, max 200) |
| apiKey | string | null | |
| clOrdId | string | null | Optional ClOrdID (tag 11) to narrow to one order |
| session* | string | |
| instance* | string |
{
"type": "object",
"required": [
"instance",
"session"
],
"properties": {
"limit": {
"type": "integer",
"default": 25,
"description": "Max rows to return, newest first (default 25, max 200)"
},
"apiKey": {
"type": [
"string",
"null"
],
"default": null
},
"clOrdId": {
"type": [
"string",
"null"
],
"default": null,
"description": "Optional ClOrdID (tag 11) to narrow to one order"
},
"session": {
"type": "string"
},
"instance": {
"type": "string"
}
}
}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.
| Argument | Type | Description |
|---|---|---|
| apiKey | string | null | FIXSIM API key. Omit when the connector sends it as a header. |
{
"type": "object",
"properties": {
"apiKey": {
"type": [
"string",
"null"
],
"default": null,
"description": "FIXSIM API key. Omit when the connector sends it as a header."
}
}
}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.
| Argument | Type | Description |
|---|---|---|
| limit | integer | Max rows to return, newest first (default 25, max 200) |
| apiKey | string | null | |
| session* | string | |
| instance* | string | |
| orderStatus | string | null | Optional FIX OrdStatus (tag 39) filter |
{
"type": "object",
"required": [
"instance",
"session"
],
"properties": {
"limit": {
"type": "integer",
"default": 25,
"description": "Max rows to return, newest first (default 25, max 200)"
},
"apiKey": {
"type": [
"string",
"null"
],
"default": null
},
"session": {
"type": "string"
},
"instance": {
"type": "string"
},
"orderStatus": {
"type": [
"string",
"null"
],
"default": null,
"description": "Optional FIX OrdStatus (tag 39) filter"
}
}
}Orders FIXSIM sent OUT on a session (created with fixsim_send_order). Pass clOrdId to fetch one.
| Argument | Type | Description |
|---|---|---|
| limit | integer | Max rows to return, newest first (default 25, max 200) |
| apiKey | string | null | |
| clOrdId | string | null | |
| session* | string | |
| instance* | string |
{
"type": "object",
"required": [
"instance",
"session"
],
"properties": {
"limit": {
"type": "integer",
"default": 25,
"description": "Max rows to return, newest first (default 25, max 200)"
},
"apiKey": {
"type": [
"string",
"null"
],
"default": null
},
"clOrdId": {
"type": [
"string",
"null"
],
"default": null
},
"session": {
"type": "string"
},
"instance": {
"type": "string"
}
}
}Securities (symbol, last price, CUSIP, ISIN) configured on an instance. FIXSIM prices fills from these.
| Argument | Type | Description |
|---|---|---|
| apiKey | string | null | |
| instance* | string |
{
"type": "object",
"required": [
"instance"
],
"properties": {
"apiKey": {
"type": [
"string",
"null"
],
"default": null
},
"instance": {
"type": "string"
}
}
}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.
| Argument | Type | Description |
|---|---|---|
| apiKey | string | null | |
| instance* | string | Instance name from fixsim_list_instances |
{
"type": "object",
"required": [
"instance"
],
"properties": {
"apiKey": {
"type": [
"string",
"null"
],
"default": null
},
"instance": {
"type": "string",
"description": "Instance name from fixsim_list_instances"
}
}
}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.
| Argument | Type | Description |
|---|---|---|
| side* | string | Side (tag 54): 1=Buy, 2=Sell, 5=Sell short |
| price | number | null | Price (tag 44), required for limit orders |
| apiKey | string | null | |
| symbol* | string | Symbol (tag 55) |
| clOrdId* | string | ClOrdID (tag 11) to assign; must be unique on the session |
| ordType* | string | OrdType (tag 40): 1=Market, 2=Limit |
| session* | string | |
| instance* | string | |
| orderQty* | number | OrderQty (tag 38) |
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.
| Argument | Type | Description |
|---|---|---|
| apiKey | string | null | |
| session* | string | |
| instance* | string | |
| fixMessages* | array | Raw FIX messages, e.g. 35=D|11=ORD1|55=IBM|54=1|38=100|40=2|44=150.25|59=0 |
{
"type": "object",
"required": [
"instance",
"session",
"fixMessages"
],
"properties": {
"apiKey": {
"type": [
"string",
"null"
],
"default": null
},
"session": {
"type": "string"
},
"instance": {
"type": "string"
},
"fixMessages": {
"type": "array",
"items": {
"type": "string"
},
"description": "Raw FIX messages, e.g. 35=D|11=ORD1|55=IBM|54=1|38=100|40=2|44=150.25|59=0"
}
}
}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.
| Argument | Type | Description |
|---|---|---|
| action* | string | fill, partial, reject or cancel |
| clOrdId* | string | ClOrdID (tag 11) of the order |
| sessionId* | string |
{
"type": "object",
"required": [
"sessionId",
"clOrdId",
"action"
],
"properties": {
"action": {
"type": "string",
"description": "fill, partial, reject or cancel"
},
"clOrdId": {
"type": "string",
"description": "ClOrdID (tag 11) of the order"
},
"sessionId": {
"type": "string",
"format": "uuid"
}
}
}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.
| Argument | Type | Description |
|---|---|---|
| fixVersion | string | FIX.4.0, FIX.4.2, FIX.4.4 (default) or FIX.5.0SP2 (rides FIXT.1.1) |
{
"type": "object",
"properties": {
"fixVersion": {
"type": "string",
"default": "FIX.4.4",
"description": "FIX.4.0, FIX.4.2, FIX.4.4 (default) or FIX.5.0SP2 (rides FIXT.1.1)"
}
}
}End a sandbox session now instead of waiting for it to expire. Frees the slot for the user's IP.
| Argument | Type | Description |
|---|---|---|
| sessionId* | string |
{
"type": "object",
"required": [
"sessionId"
],
"properties": {
"sessionId": {
"type": "string",
"format": "uuid"
}
}
}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.
| Argument | Type | Description |
|---|---|---|
| afterSeq | integer | Return only messages with seq greater than this |
| sessionId* | string |
{
"type": "object",
"required": [
"sessionId"
],
"properties": {
"afterSeq": {
"type": "integer",
"default": 0,
"description": "Return only messages with seq greater than this"
},
"sessionId": {
"type": "string",
"format": "uuid"
}
}
}Working orders the user's engine has sent into the sandbox session: ClOrdID, symbol, side, qty, filled, leaves, price, status.
| Argument | Type | Description |
|---|---|---|
| sessionId* | string |
{
"type": "object",
"required": [
"sessionId"
],
"properties": {
"sessionId": {
"type": "string",
"format": "uuid"
}
}
}Re-fetch a sandbox session's connection card by id, including whether auto-fill is on and when it expires.
| Argument | Type | Description |
|---|---|---|
| sessionId* | string | Session id from sandbox_create_session |
{
"type": "object",
"required": [
"sessionId"
],
"properties": {
"sessionId": {
"type": "string",
"format": "uuid",
"description": "Session id from sandbox_create_session"
}
}
}Is the user's FIX engine connected to the sandbox session? Returns state: connected, waiting (nobody logged on yet), disabled, or unknown.
| Argument | Type | Description |
|---|---|---|
| sessionId* | string |
{
"type": "object",
"required": [
"sessionId"
],
"properties": {
"sessionId": {
"type": "string",
"format": "uuid"
}
}
}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.
| Argument | Type | Description |
|---|---|---|
| enabled* | boolean | |
| sessionId* | string |
{
"type": "object",
"required": [
"sessionId",
"enabled"
],
"properties": {
"enabled": {
"type": "boolean"
},
"sessionId": {
"type": "string",
"format": "uuid"
}
}
}| additionalTags |
| array | null |
| Extra FIX tags, e.g. [{tag:59,value:"0"}] |
{
"type": "object",
"required": [
"instance",
"session",
"clOrdId",
"symbol",
"side",
"orderQty",
"ordType"
],
"properties": {
"side": {
"type": "string",
"description": "Side (tag 54): 1=Buy, 2=Sell, 5=Sell short"
},
"price": {
"type": [
"number",
"null"
],
"default": null,
"description": "Price (tag 44), required for limit orders"
},
"apiKey": {
"type": [
"string",
"null"
],
"default": null
},
"symbol": {
"type": "string",
"description": "Symbol (tag 55)"
},
"clOrdId": {
"type": "string",
"description": "ClOrdID (tag 11) to assign; must be unique on the session"
},
"ordType": {
"type": "string",
"description": "OrdType (tag 40): 1=Market, 2=Limit"
},
"session": {
"type": "string"
},
"instance": {
"type": "string"
},
"orderQty": {
"type": "number",
"description": "OrderQty (tag 38)"
},
"additionalTags": {
"type": [
"array",
"null"
],
"items": {
"type": [
"object",
"null"
],
"required": [
"tag",
"value"
],
"properties": {
"tag": {
"type": "integer"
},
"value": {
"type": [
"string",
"null"
]
}
}
},
"default": null,
"description": "Extra FIX tags, e.g. [{tag:59,value:\"0\"}]"
}
}
}