diff --git a/.golangci.yml b/.golangci.yml
new file mode 100644
index 0000000..8791a5b
--- /dev/null
+++ b/.golangci.yml
@@ -0,0 +1,19 @@
+version: "2"
+
+run:
+  timeout: 5m
+
+linters:
+  enable:
+    - gocritic
+    - godot
+    - misspell
+    - whitespace
+
+settings:
+  godot:
+    scope: declarations
+    capital: false
+  gocritic:
+    enabled-checks:
+      - ifElseChain
diff --git a/pkg/commit/normalizer.go b/pkg/commit/normalizer.go
new file mode 100644
index 0000000..7b935ca
--- /dev/null
+++ b/pkg/commit/normalizer.go
@@ -0,0 +1,309 @@
+package commit
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+	"unicode"
+)
+
+// CommitType represents valid conventional commit types.
+type CommitType string
+
+const (
+	TypeFeat     CommitType = "feat"
+	TypeFix      CommitType = "fix"
+	TypeDocs     CommitType = "docs"
+	TypeStyle    CommitType = "style"
+	TypeRefactor CommitType = "refactor"
+	TypePerf     CommitType = "perf"
+	TypeTest     CommitType = "test"
+	TypeBuild    CommitType = "build"
+	TypeCI       CommitType = "ci"
+	TypeChore    CommitType = "chore"
+	TypeRevert   CommitType = "revert"
+)
+
+const (
+	// MaxSubjectLength is the maximum length for a commit subject line.
+	MaxSubjectLength = 72
+	// MaxBodyLineLength is the maximum length for body lines.
+	MaxBodyLineLength = 100
+)
+
+var (
+	// validTypes contains all valid commit types.
+	validTypes = map[string]CommitType{
+		"feat":     TypeFeat,
+		"fix":      TypeFix,
+		"docs":     TypeDocs,
+		"style":    TypeStyle,
+		"refactor": TypeRefactor,
+		"perf":     TypePerf,
+		"test":     TypeTest,
+		"build":    TypeBuild,
+		"ci":       TypeCI,
+		"chore":    TypeChore,
+		"revert":   TypeRevert,
+	}
+
+	// commitPattern matches conventional commit format: type(scope): subject
+	// Also supports breaking change indicator with !
+	commitPattern = regexp.MustCompile(`^([a-z]+)(\(([^)]+)\))?!?: (.+)$`)
+)
+
+// CommitMessage represents a parsed commit message.
+type CommitMessage struct {
+	Type          CommitType
+	Scope         string
+	Subject       string
+	Body          string
+	Footer        string
+	BreakingChange bool
+}
+
+// ValidationError represents a commit message validation error.
+type ValidationError struct {
+	Field   string
+	Message string
+}
+
+func (e *ValidationError) Error() string {
+	return fmt.Sprintf("%s: %s", e.Field, e.Message)
+}
+
+// Parse parses a commit message string into a CommitMessage struct.
+func Parse(message string) (*CommitMessage, error) {
+	lines := strings.Split(message, "\n")
+	if len(lines) == 0 || strings.TrimSpace(lines[0]) == "" {
+		return nil, &ValidationError{Field: "message", Message: "commit message cannot be empty"}
+	}
+
+	subject := strings.TrimSpace(lines[0])
+	matches := commitPattern.FindStringSubmatch(subject)
+
+	if matches == nil {
+		return nil, &ValidationError{
+			Field:   "subject",
+			Message: "subject must follow format: type(scope): description",
+		}
+	}
+
+	typeStr := matches[1]
+	scope := matches[3]
+	description := matches[4]
+
+	// Validate type
+	commitType, valid := validTypes[typeStr]
+	if !valid {
+		return nil, &ValidationError{
+			Field:   "type",
+			Message: fmt.Sprintf("invalid type '%s', must be one of: %s", typeStr, getValidTypesString()),
+		}
+	}
+
+	// Parse body and footer
+	var body, footer string
+	var breakingChange bool
+
+	if len(lines) > 1 {
+		// Skip the blank line after subject if present
+		bodyStart := 1
+		if bodyStart < len(lines) && strings.TrimSpace(lines[bodyStart]) == "" {
+			bodyStart = 2
+		}
+
+		// Find footer start (lines starting with BREAKING CHANGE: or other tokens)
+		footerStart := -1
+		for i := bodyStart; i < len(lines); i++ {
+			line := strings.TrimSpace(lines[i])
+			if strings.HasPrefix(line, "BREAKING CHANGE:") ||
+				strings.HasPrefix(line, "Fixes:") ||
+				strings.HasPrefix(line, "Closes:") ||
+				strings.HasPrefix(line, "Refs:") {
+				footerStart = i
+				break
+			}
+		}
+
+		switch {
+		case footerStart > bodyStart:
+			body = strings.Join(lines[bodyStart:footerStart], "\n")
+			footer = strings.Join(lines[footerStart:], "\n")
+		case footerStart == bodyStart:
+			footer = strings.Join(lines[footerStart:], "\n")
+		case bodyStart < len(lines):
+			body = strings.Join(lines[bodyStart:], "\n")
+		}
+
+		body = strings.TrimSpace(body)
+		footer = strings.TrimSpace(footer)
+
+		if strings.Contains(footer, "BREAKING CHANGE:") || strings.Contains(subject, "!") {
+			breakingChange = true
+		}
+	}
+
+	return &CommitMessage{
+		Type:           commitType,
+		Scope:          scope,
+		Subject:        description,
+		Body:           body,
+		Footer:         footer,
+		BreakingChange: breakingChange,
+	}, nil
+}
+
+// Normalize takes a commit message and returns a normalized version
+// following conventional commits format.
+func Normalize(message string) (string, error) {
+	cm, err := Parse(message)
+	if err != nil {
+		return "", err
+	}
+
+	return cm.Format(), nil
+}
+
+// Format formats the CommitMessage into a conventional commit string.
+func (cm *CommitMessage) Format() string {
+	var parts []string
+
+	// Format subject line
+	subject := formatSubject(cm.Type, cm.Scope, cm.Subject)
+	parts = append(parts, subject)
+
+	// Add blank line before body if body exists
+	if cm.Body != "" {
+		parts = append(parts, "")
+		parts = append(parts, wrapText(cm.Body, MaxBodyLineLength))
+	}
+
+	// Add blank line before footer if footer exists
+	if cm.Footer != "" {
+		parts = append(parts, "")
+		parts = append(parts, cm.Footer)
+	}
+
+	return strings.Join(parts, "\n")
+}
+
+// Validate validates the commit message against conventional commits rules.
+func (cm *CommitMessage) Validate() error {
+	// Validate type
+	if _, valid := validTypes[string(cm.Type)]; !valid {
+		return &ValidationError{
+			Field:   "type",
+			Message: fmt.Sprintf("invalid type '%s'", cm.Type),
+		}
+	}
+
+	// Validate subject
+	if cm.Subject == "" {
+		return &ValidationError{Field: "subject", Message: "subject cannot be empty"}
+	}
+
+	// Check subject capitalization (should not start with capital letter)
+	if unicode.IsUpper(rune(cm.Subject[0])) {
+		return &ValidationError{
+			Field:   "subject",
+			Message: "subject should start with lowercase letter",
+		}
+	}
+
+	// Check subject doesn't end with period
+	if strings.HasSuffix(cm.Subject, ".") {
+		return &ValidationError{
+			Field:   "subject",
+			Message: "subject should not end with period",
+		}
+	}
+
+	// Check subject length
+	subjectLine := formatSubject(cm.Type, cm.Scope, cm.Subject)
+	if len(subjectLine) > MaxSubjectLength {
+		return &ValidationError{
+			Field:   "subject",
+			Message: fmt.Sprintf("subject line too long (%d > %d)", len(subjectLine), MaxSubjectLength),
+		}
+	}
+
+	return nil
+}
+
+// formatSubject formats the subject line with type and optional scope.
+func formatSubject(commitType CommitType, scope, subject string) string {
+	if scope != "" {
+		return fmt.Sprintf("%s(%s): %s", commitType, scope, subject)
+	}
+	return fmt.Sprintf("%s: %s", commitType, subject)
+}
+
+// wrapText wraps text to the specified line length.
+func wrapText(text string, maxLength int) string {
+	if text == "" {
+		return text
+	}
+
+	var result []string
+	paragraphs := strings.Split(text, "\n\n")
+
+	for i, paragraph := range paragraphs {
+		paragraph = strings.TrimSpace(paragraph)
+		if paragraph == "" {
+			continue
+		}
+
+		// Handle already-formatted lines (like lists)
+		if strings.HasPrefix(paragraph, "- ") || strings.HasPrefix(paragraph, "* ") {
+			result = append(result, paragraph)
+			if i < len(paragraphs)-1 {
+				result = append(result, "")
+			}
+			continue
+		}
+
+		words := strings.Fields(paragraph)
+		if len(words) == 0 {
+			continue
+		}
+
+		var line string
+		for _, word := range words {
+			switch {
+			case line == "":
+				line = word
+			case len(line)+1+len(word) <= maxLength:
+				line = line + " " + word
+			default:
+				result = append(result, line)
+				line = word
+			}
+		}
+		if line != "" {
+			result = append(result, line)
+		}
+
+		// Add blank line between paragraphs
+		if i < len(paragraphs)-1 {
+			result = append(result, "")
+		}
+	}
+
+	return strings.Join(result, "\n")
+}
+
+// getValidTypesString returns a comma-separated list of valid types.
+func getValidTypesString() string {
+	types := make([]string, 0, len(validTypes))
+	for t := range validTypes {
+		types = append(types, t)
+	}
+	return strings.Join(types, ", ")
+}
+
+// IsValidType checks if a string is a valid commit type.
+func IsValidType(t string) bool {
+	_, valid := validTypes[t]
+	return valid
+}