diff --git a/api/api.go b/api/api.go
new file mode 100644
index 0000000000..9fda6fa012
--- /dev/null
+++ b/api/api.go
@@ -0,0 +1,11 @@
+package api
+
+import (
+        "code.google.com/p/gorest"
+)
+
+type MetricsService struct {
+        gorest.RestService `root:"/api/" consumes:"application/json" produces:"application/json"`
+
+        query gorest.EndPoint `method:"GET" path:"/query?{expr:string}&{json:string}&{start:string}&{end:string}" output:"string"`
+}
diff --git a/api/query.go b/api/query.go
new file mode 100644
index 0000000000..6d5ff33d59
--- /dev/null
+++ b/api/query.go
@@ -0,0 +1,21 @@
+package api
+
+import (
+	"github.com/matttproud/prometheus/rules"
+	"github.com/matttproud/prometheus/rules/ast"
+        "time"
+)
+func (serv MetricsService) Query(Expr string, Json string, Start string, End string) (result string) {
+        exprNode, err := rules.LoadExprFromString(Expr)
+        if err != nil {
+                return err.Error()
+        }
+
+        timestamp := time.Now()
+
+        format := ast.TEXT
+        if Json != "" {
+                format = ast.JSON
+        }
+        return ast.EvalToString(exprNode, &timestamp, format)
+}
diff --git a/main.go b/main.go
index d47add1e92..1546a98947 100644
--- a/main.go
+++ b/main.go
@@ -14,7 +14,9 @@
 package main
 
 import (
+        "code.google.com/p/gorest"
 	"fmt"
+	"github.com/matttproud/prometheus/api"
 	"github.com/matttproud/golang_instrumentation"
 	"github.com/matttproud/prometheus/config"
 	"github.com/matttproud/prometheus/retrieval"
@@ -66,20 +68,24 @@ func main() {
 	}
 
 	go func() {
+                gorest.RegisterService(new(api.MetricsService))
 		exporter := registry.DefaultRegistry.YieldExporter()
+
+                http.Handle("/", gorest.Handle())
 		http.Handle("/metrics.json", exporter)
+                http.Handle("/static/", http.StripPrefix("/static/", http.FileServer(http.Dir("static"))))
 		http.ListenAndServe(":9090", nil)
 	}()
 
 	for {
 		select {
 		case scrapeResult := <-scrapeResults:
-			fmt.Printf("scrapeResult -> %s\n", scrapeResult)
+			//fmt.Printf("scrapeResult -> %s\n", scrapeResult)
 			for _, sample := range scrapeResult.Samples {
 				persistence.AppendSample(&sample)
 			}
 		case ruleResult := <-ruleResults:
-			fmt.Printf("ruleResult -> %s\n", ruleResult)
+			//fmt.Printf("ruleResult -> %s\n", ruleResult)
 			for _, sample := range ruleResult.Samples {
 				persistence.AppendSample(sample)
 			}
diff --git a/rules/ast/printer.go b/rules/ast/printer.go
index 2baf65166b..3738af375b 100644
--- a/rules/ast/printer.go
+++ b/rules/ast/printer.go
@@ -2,11 +2,19 @@ package ast
 
 import (
 	"fmt"
+        "encoding/json"
 	"sort"
 	"strings"
 	"time"
 )
 
+type OutputFormat int
+
+const (
+        TEXT OutputFormat = iota
+        JSON
+)
+
 func binOpTypeToString(opType BinOpType) string {
 	opTypeMap := map[BinOpType]string{
 		ADD: "+",
@@ -34,6 +42,16 @@ func aggrTypeToString(aggrType AggrType) string {
 	return aggrTypeMap[aggrType]
 }
 
+func exprTypeToString(exprType ExprType) string {
+	exprTypeMap := map[ExprType]string{
+		SCALAR: "scalar",
+		VECTOR: "vector",
+		MATRIX: "matrix",
+		STRING: "string",
+	}
+	return exprTypeMap[exprType]
+}
+
 func durationToString(duration time.Duration) string {
 	seconds := int64(duration / time.Second)
 	factors := map[string]int64{
@@ -81,6 +99,96 @@ func (vector Vector) ToString() string {
 	return strings.Join(metricStrings, "\n")
 }
 
+func (matrix Matrix) ToString() string {
+	metricStrings := []string{}
+	for _, sampleSet := range matrix {
+		metricName, ok := sampleSet.Metric["name"]
+		if !ok {
+			panic("Tried to print matrix without metric name")
+		}
+		labelStrings := []string{}
+		for label, value := range sampleSet.Metric {
+			if label != "name" {
+				labelStrings = append(labelStrings, fmt.Sprintf("%v='%v'", label, value))
+			}
+		}
+		sort.Strings(labelStrings)
+                valueStrings := []string{}
+                for _, value := range sampleSet.Values {
+                        valueStrings = append(valueStrings,
+                                              fmt.Sprintf("\n%v @[%v]", value.Value, value.Timestamp))
+                }
+		metricStrings = append(metricStrings,
+			fmt.Sprintf("%v{%v} => %v",
+				metricName,
+				strings.Join(labelStrings, ","),
+				strings.Join(valueStrings, ", ")))
+	}
+	sort.Strings(metricStrings)
+	return strings.Join(metricStrings, "\n")
+}
+
+func errorToJSON(err error) string {
+        errorStruct := struct {
+                Type string
+                Error string
+        }{
+                Type: "error",
+                Error: err.Error(),
+        }
+
+        errorJSON, err := json.MarshalIndent(errorStruct, "", "\t")
+        if err != nil {
+                return ""
+        }
+        return string(errorJSON)
+}
+
+func typedValueToJSON(data interface{}, typeStr string) string {
+        dataStruct := struct {
+                Type string
+                Value interface{}
+        }{
+                Type: typeStr,
+                Value: data,
+        }
+        dataJSON, err := json.MarshalIndent(dataStruct, "", "\t")
+        if err != nil {
+                return errorToJSON(err)
+        }
+        return string(dataJSON)
+}
+
+func EvalToString(node Node, timestamp *time.Time, format OutputFormat) string {
+        switch node.Type() {
+        case SCALAR:
+                scalar := node.(ScalarNode).Eval(timestamp)
+                switch format {
+                case TEXT: return fmt.Sprintf("scalar: %v", scalar)
+                case JSON: return typedValueToJSON(scalar, "scalar")
+                }
+        case VECTOR:
+                vector := node.(VectorNode).Eval(timestamp)
+                switch format {
+                case TEXT: return vector.ToString()
+                case JSON: return typedValueToJSON(vector, "vector")
+                }
+        case MATRIX:
+                matrix := node.(MatrixNode).Eval(timestamp)
+                switch format {
+                case TEXT: return matrix.ToString()
+                case JSON: return typedValueToJSON(matrix, "matrix")
+                }
+        case STRING:
+                str := node.(StringNode).Eval(timestamp)
+                switch format {
+                case TEXT: return str
+                case JSON: return typedValueToJSON(str, "string")
+                }
+        }
+        panic("Switch didn't cover all node types")
+}
+
 func (node *VectorLiteral) ToString() string {
 	metricName, ok := node.labels["name"]
 	if !ok {