What is the FIX Protocol?

The Financial Information eXchange (FIX) protocol is the global standard electronic messaging specification for securities transactions, order routing, trade execution reports, and market data dissemination across institutional exchanges, brokerages, and algorithmic trading desks.

Is my trading data, order flow, or API key safe using this parser?

100% yes. All message tokenization, ASCII byte summation, dictionary lookup, and rendering occur entirely in your local browser memory. Zero bytes of your message are ever transmitted over the network or saved to any remote server.

How is the CheckSum (Tag 10) calculated and validated?

Tag 10 CheckSum is calculated as the modulo-256 sum of the ASCII byte values of all characters from the very beginning of the message (the '8' of 8=FIX) up to and including the delimiter immediately preceding Tag 10. The result is formatted as a 3-digit zero-padded number (e.g., 084). Our parser verifies this sum against the declared Tag 10 value in real time.

How is BodyLength (Tag 9) calculated?

BodyLength represents the character byte count starting immediately after the delimiter terminating Tag 9, up to and including the delimiter immediately terminating the field prior to Tag 10. The parser calculates the exact UTF-8 byte count and reports any discrepancies with declared lengths.

What delimiters does this parser support?

The parser auto-detects standard ASCII SOH (\x01), pipe (|), caret (^) or caret-A (^A), semicolons (;), spaces, and custom user-defined delimiters.

How are repeating groups rendered?

Counter tags (such as NoMDEntries Tag 268 or NoPartyIDs Tag 453) are automatically recognized. Child tags belonging to each repeating entry are nested under interactive, collapsible group cards with entry count verification.

Does this tool work completely offline?

Yes. All FIX dictionary specifications and parsing routines are bundled client-side and pre-cached by the Service Worker, enabling full offline operation with zero internet connection.

FIX Protocol Parser

Decode and validate FIX protocol messages online. Free, 100% private client-side FIX parser supporting FIX 4.0-5.0SP2, SOH/pipe delimiters, checksum & body length checks.

Raw logs1 message loaded• 100% Client-Side Memory

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Sample:

Strip log prefixes

Lines: 1 • Chars: 183 • Delim: |

Timeline

1 message

Skip session msgs

Msg #	Time	Sender	Message	Detail
	20260910-14:30:00.120	ALPHA_CAPITAL	New Order - Single	Buy 500 NVDA @ 128.50

Detail

35=DNew Order - Single

CheckSum: PASS (199)

BodyLength: PASS (160)

8=FIX.4.4|9=160|35=D|49=ALPHA_CAPITAL|56=MORGAN_DESK|34=1024|52=20260910-14:30:00.120|11=ORD_20260910_001|21=1|55=NVDA|54=1|60=20260910-14:30:00.118|38=500|40=2|44=128.50|59=0|10=199

Tag	Field Name	Raw Value	Decoded Meaning
Tag 8	BeginString	FIX.4.4	FIX 4.4
Tag 9	BodyLength	160	160 Bytes (Header-to-Checksum Length)
Tag 35	MsgType	D	New Order - Single
Tag 49	SenderCompID	ALPHA_CAPITAL	Sender Firm / Desk Identifier
Tag 56	TargetCompID	MORGAN_DESK	Target Firm / Desk Identifier
Tag 34	MsgSeqNum	1024	Message Sequence #1,024
Tag 52	SendingTime	20260910-14:30:00.120	Sep 10, 2026 14:30:00.120 UTC (Sent)
Tag 11	ClOrdID	ORD_20260910_001	Client Assigned Order ID
Tag 21	HandlInst	1	Automated private
Tag 55	Symbol	NVDA	Trading Instrument Symbol
Tag 54	Side	1	Buy
Tag 60	TransactTime	20260910-14:30:00.118	Sep 10, 2026 14:30:00.118 UTC (Transacted)
Tag 38	OrderQty	500	500 Shares / Contracts
Tag 40	OrdType	2	Limit
Tag 44	Price	128.50	$128.50 (Limit Price)
Tag 59	TimeInForce	0	Day
Tag 10	CheckSum	199	199 (Modulo-256 Checksum)

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FIX Protocol Parser

Timeline

Detail

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