FIX Protocol Tag=Value Pair Regex for Go

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching fix protocol tag=value pair, ported and verified for Go. Financial data validation has zero tolerance for false negatives — a missed invalid entry can corrupt downstream calculations. The snippet below is ready to drop into your Go project — whether you're validating in a Gin handler, a gRPC service, or a command-line tool.

Go Implementation

// FIX Protocol Tag=Value Pair
// ReDoS-safe | RegexVault — Finance > Securities & Trading

package validation

import "regexp"

var fixProtocolTagvaluePairRe = regexp.MustCompile(`^[0-9]+=[^\x01\s]+$`)

func ValidateFixProtocolTagvaluePair(s string) bool {
    return fixProtocolTagvaluePairRe.MatchString(s)
}

// Example
// fmt.Println(ValidateFixProtocolTagvaluePair("35=D")) // true

Test Cases

When to use this pattern

This pattern is drawn from the Finance > Securities & Trading category and carries a ReDoS-safe certification. That matters for Go developers because Go's RE2 engine is inherently safe from catastrophic backtracking, but this pattern has been additionally verified for correctness. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

FIX protocol separates fields with SOH (\x01, ASCII 001). This pattern matches a single field — strip the SOH delimiter before matching individual pairs. Capture group 1: tag number, group 2: value. Tag 35 is MsgType.