diff --git a/internal/condition/evaluator.go b/internal/condition/evaluator.go
new file mode 100644
index 0000000..41957c2
--- /dev/null
+++ b/internal/condition/evaluator.go
@@ -0,0 +1,98 @@
+package condition
+
+import (
+	"encoding/json"
+	"fmt"
+	"strconv"
+	"strings"
+
+	"aiaa-notification-service/internal/model"
+)
+
+// Evaluate checks all conditions against data. Returns true if ALL conditions pass.
+// An empty conditions slice always returns true.
+func Evaluate(conditions []model.Condition, data map[string]interface{}) bool {
+	if len(conditions) == 0 {
+		return true
+	}
+	for _, c := range conditions {
+		if !evaluateOne(c, data) {
+			return false
+		}
+	}
+	return true
+}
+
+func evaluateOne(c model.Condition, data map[string]interface{}) bool {
+	fieldVal, fieldExists := data[c.Field]
+
+	switch c.Op {
+	case "exists":
+		return fieldExists
+	case "not_exists":
+		return !fieldExists
+	case "eq":
+		if !fieldExists {
+			return false
+		}
+		return fmt.Sprintf("%v", fieldVal) == c.Value
+	case "ne":
+		if !fieldExists {
+			return false
+		}
+		return fmt.Sprintf("%v", fieldVal) != c.Value
+	case "contains":
+		if !fieldExists {
+			return false
+		}
+		return strings.Contains(fmt.Sprintf("%v", fieldVal), c.Value)
+	case "gt", "gte", "lt", "lte":
+		if !fieldExists {
+			return false
+		}
+		return compareNumeric(fieldVal, c.Value, c.Op)
+	default:
+		return false
+	}
+}
+
+func compareNumeric(fieldVal interface{}, value string, op string) bool {
+	fv, err := toFloat64(fieldVal)
+	if err != nil {
+		return false
+	}
+	cv, err := strconv.ParseFloat(value, 64)
+	if err != nil {
+		return false
+	}
+	switch op {
+	case "gt":
+		return fv > cv
+	case "gte":
+		return fv >= cv
+	case "lt":
+		return fv < cv
+	case "lte":
+		return fv <= cv
+	}
+	return false
+}
+
+func toFloat64(v interface{}) (float64, error) {
+	switch val := v.(type) {
+	case float64:
+		return val, nil
+	case float32:
+		return float64(val), nil
+	case int:
+		return float64(val), nil
+	case int64:
+		return float64(val), nil
+	case string:
+		return strconv.ParseFloat(val, 64)
+	case json.Number:
+		return val.Float64()
+	default:
+		return 0, fmt.Errorf("cannot convert %T to float64", v)
+	}
+}
diff --git a/internal/condition/evaluator_test.go b/internal/condition/evaluator_test.go
new file mode 100644
index 0000000..310815b
--- /dev/null
+++ b/internal/condition/evaluator_test.go
@@ -0,0 +1,56 @@
+package condition
+
+import (
+	"testing"
+
+	"aiaa-notification-service/internal/model"
+)
+
+func TestEvaluate_Empty(t *testing.T) {
+	if !Evaluate(nil, nil) {
+		t.Error("empty conditions should pass")
+	}
+}
+
+func TestEvaluate_Exists(t *testing.T) {
+	conds := []model.Condition{{Field: "symbol", Op: "exists"}}
+	data := map[string]interface{}{"symbol": "BTC"}
+	if !Evaluate(conds, data) {
+		t.Error("symbol exists, should pass")
+	}
+}
+
+func TestEvaluate_NotExists(t *testing.T) {
+	conds := []model.Condition{{Field: "symbol", Op: "not_exists"}}
+	data := map[string]interface{}{"price": 100}
+	if !Evaluate(conds, data) {
+		t.Error("symbol not exists, should pass")
+	}
+}
+
+func TestEvaluate_Gt(t *testing.T) {
+	conds := []model.Condition{{Field: "price", Op: "gt", Value: "100"}}
+	data := map[string]interface{}{"price": float64(200)}
+	if !Evaluate(conds, data) {
+		t.Error("200 > 100, should pass")
+	}
+}
+
+func TestEvaluate_Fail(t *testing.T) {
+	conds := []model.Condition{
+		{Field: "symbol", Op: "exists"},
+		{Field: "price", Op: "lt", Value: "100"},
+	}
+	data := map[string]interface{}{"symbol": "BTC", "price": float64(200)}
+	if Evaluate(conds, data) {
+		t.Error("200 < 100 is false, should fail")
+	}
+}
+
+func TestEvaluate_Contains(t *testing.T) {
+	conds := []model.Condition{{Field: "msg", Op: "contains", Value: "error"}}
+	data := map[string]interface{}{"msg": "connection error occurred"}
+	if !Evaluate(conds, data) {
+		t.Error("msg contains 'error', should pass")
+	}
+}