diff --git a/internal/reqdata/parameter.go b/internal/reqdata/parameter.go
index 4bceb95..2c80455 100644
--- a/internal/reqdata/parameter.go
+++ b/internal/reqdata/parameter.go
@@ -4,8 +4,19 @@ import (
 	"encoding/json"
 	"fmt"
 	"reflect"
+
+	"git.xdrm.io/go/aicra/internal/cerr"
 )
 
+// ErrUnknownType is returned when encountering an unknown type
+const ErrUnknownType = cerr.Error("unknown type")
+
+// ErrInvalidJSON is returned when json parse failed
+const ErrInvalidJSON = cerr.Error("invalid json")
+
+// ErrInvalidRootType is returned when json is a map
+const ErrInvalidRootType = cerr.Error("invalid json root type")
+
 // Parameter represents an http request parameter
 // that can be of type URL, GET, or FORM (multipart, json, urlencoded)
 type Parameter struct {
@@ -22,16 +33,23 @@ type Parameter struct {
 }
 
 // Parse parameter (json-like) if not already done
-func (i *Parameter) Parse() {
+func (i *Parameter) Parse() error {
 
 	/* (1) Stop if already parsed or nil*/
 	if i.Parsed || i.Value == nil {
-		return
+		return nil
 	}
 
 	/* (2) Try to parse value */
-	i.Value = parseParameter(i.Value)
+	parsed, err := parseParameter(i.Value)
+	if err != nil {
+		return err
+	}
 
+	i.Parsed = true
+	i.Value = parsed
+
+	return nil
 }
 
 // parseParameter parses http GET/POST data
@@ -39,7 +57,7 @@ func (i *Parameter) Parse() {
 //		- size = 1 : return json of first element
 //		- size > 1 : return array of json elements
 // - string : return json if valid, else return raw string
-func parseParameter(data interface{}) interface{} {
+func parseParameter(data interface{}) (interface{}, error) {
 	dtype := reflect.TypeOf(data)
 	dvalue := reflect.ValueOf(data)
 
@@ -48,23 +66,12 @@ func parseParameter(data interface{}) interface{} {
 	/* (1) []string -> recursive */
 	case reflect.Slice:
 
-		// 1. Return nothing if empty
+		// 1. ignore empty
 		if dvalue.Len() == 0 {
-			return nil
+			return data, nil
 		}
 
-		// 2. only return first element if alone
-		if dvalue.Len() == 1 {
-
-			element := dvalue.Index(0)
-			if element.Kind() != reflect.String {
-				return nil
-			}
-			return parseParameter(element.String())
-
-		}
-
-		// 3. Return all elements if more than 1
+		// 2. parse each element recursively
 		result := make([]interface{}, dvalue.Len())
 
 		for i, l := 0, dvalue.Len(); i < l; i++ {
@@ -72,12 +79,17 @@ func parseParameter(data interface{}) interface{} {
 
 			// ignore non-string
 			if element.Kind() != reflect.String {
+				result[i] = element.Interface()
 				continue
 			}
 
-			result[i] = parseParameter(element.String())
+			parsed, err := parseParameter(element.String())
+			if err != nil {
+				return data, err
+			}
+			result[i] = parsed
 		}
-		return result
+		return result, nil
 
 	/* (2) string -> parse */
 	case reflect.String:
@@ -94,23 +106,23 @@ func parseParameter(data interface{}) interface{} {
 
 			mapval, ok := result.(map[string]interface{})
 			if !ok {
-				return dvalue.String()
+				return dvalue.String(), ErrInvalidRootType
 			}
 
 			wrapped, ok := mapval["wrapped"]
 			if !ok {
-				return dvalue.String()
+				return dvalue.String(), ErrInvalidJSON
 			}
 
-			return wrapped
+			return wrapped, nil
 		}
 
 		// else return as string
-		return dvalue.String()
+		return dvalue.String(), nil
 
 	}
 
 	/* (3) NIL if unknown type */
-	return dvalue
+	return dvalue.Interface(), nil
 
 }
diff --git a/internal/reqdata/parameter_test.go b/internal/reqdata/parameter_test.go
new file mode 100644
index 0000000..29bcbec
--- /dev/null
+++ b/internal/reqdata/parameter_test.go
@@ -0,0 +1,358 @@
+package reqdata
+
+import (
+	"math"
+	"testing"
+)
+
+func TestSimpleString(t *testing.T) {
+	p := Parameter{Parsed: false, File: false, Value: "some-string"}
+
+	err := p.Parse()
+
+	if err != nil {
+		t.Errorf("unexpected error: <%s>", err)
+		t.FailNow()
+	}
+
+	if !p.Parsed {
+		t.Errorf("expected parameter to be parsed")
+		t.FailNow()
+	}
+
+	cast, canCast := p.Value.(string)
+	if !canCast {
+		t.Errorf("expected parameter to be a string")
+		t.FailNow()
+	}
+
+	if cast != "some-string" {
+		t.Errorf("expected parameter to equal 'some-string', got '%s'", cast)
+		t.FailNow()
+	}
+}
+
+func TestSimpleFloat(t *testing.T) {
+	tcases := []float64{12.3456789, -12.3456789, 0.0000001, -0.0000001}
+
+	for i, tcase := range tcases {
+		t.Run("case "+string(i), func(t *testing.T) {
+			p := Parameter{Parsed: false, File: false, Value: tcase}
+
+			if err := p.Parse(); err != nil {
+				t.Errorf("unexpected error: <%s>", err)
+				t.FailNow()
+			}
+
+			if !p.Parsed {
+				t.Errorf("expected parameter to be parsed")
+				t.FailNow()
+			}
+
+			cast, canCast := p.Value.(float64)
+			if !canCast {
+				t.Errorf("expected parameter to be a float64")
+				t.FailNow()
+			}
+
+			if math.Abs(cast-tcase) > 0.00000001 {
+				t.Errorf("expected parameter to equal '%f', got '%f'", tcase, cast)
+				t.FailNow()
+			}
+		})
+	}
+}
+
+func TestSimpleBool(t *testing.T) {
+	tcases := []bool{true, false}
+
+	for i, tcase := range tcases {
+		t.Run("case "+string(i), func(t *testing.T) {
+			p := Parameter{Parsed: false, File: false, Value: tcase}
+
+			if err := p.Parse(); err != nil {
+				t.Errorf("unexpected error: <%s>", err)
+				t.FailNow()
+			}
+
+			if !p.Parsed {
+				t.Errorf("expected parameter to be parsed")
+				t.FailNow()
+			}
+
+			cast, canCast := p.Value.(bool)
+			if !canCast {
+				t.Errorf("expected parameter to be a bool")
+				t.FailNow()
+			}
+
+			if cast != tcase {
+				t.Errorf("expected parameter to equal '%t', got '%t'", tcase, cast)
+				t.FailNow()
+			}
+		})
+	}
+}
+
+func TestJsonStringSlice(t *testing.T) {
+	p := Parameter{Parsed: false, File: false, Value: `["str1", "str2"]`}
+
+	err := p.Parse()
+
+	if err != nil {
+		t.Errorf("unexpected error: <%s>", err)
+		t.FailNow()
+	}
+
+	if !p.Parsed {
+		t.Errorf("expected parameter to be parsed")
+		t.FailNow()
+	}
+
+	slice, canCast := p.Value.([]interface{})
+	if !canCast {
+		t.Errorf("expected parameter to be a []interface{}")
+		t.FailNow()
+	}
+
+	if len(slice) != 2 {
+		t.Errorf("expected 2 values, got %d", len(slice))
+		t.FailNow()
+	}
+
+	results := []string{"str1", "str2"}
+
+	for i, res := range results {
+
+		cast, canCast := slice[i].(string)
+		if !canCast {
+			t.Errorf("expected parameter %d to be a []string", i)
+			continue
+		}
+		if cast != res {
+			t.Errorf("expected first value to be '%s', got '%s'", res, cast)
+			continue
+		}
+
+	}
+
+}
+
+func TestStringSlice(t *testing.T) {
+	p := Parameter{Parsed: false, File: false, Value: []string{"str1", "str2"}}
+
+	err := p.Parse()
+
+	if err != nil {
+		t.Errorf("unexpected error: <%s>", err)
+		t.FailNow()
+	}
+
+	if !p.Parsed {
+		t.Errorf("expected parameter to be parsed")
+		t.FailNow()
+	}
+
+	slice, canCast := p.Value.([]interface{})
+	if !canCast {
+		t.Errorf("expected parameter to be a []interface{}")
+		t.FailNow()
+	}
+
+	if len(slice) != 2 {
+		t.Errorf("expected 2 values, got %d", len(slice))
+		t.FailNow()
+	}
+
+	results := []string{"str1", "str2"}
+
+	for i, res := range results {
+
+		cast, canCast := slice[i].(string)
+		if !canCast {
+			t.Errorf("expected parameter %d to be a []string", i)
+			continue
+		}
+		if cast != res {
+			t.Errorf("expected first value to be '%s', got '%s'", res, cast)
+			continue
+		}
+
+	}
+
+}
+
+func TestJsonPrimitiveBool(t *testing.T) {
+	tcases := []struct {
+		Raw       string
+		BoolValue bool
+	}{
+		{"true", true},
+		{"false", false},
+	}
+
+	for i, tcase := range tcases {
+		t.Run("case "+string(i), func(t *testing.T) {
+			p := Parameter{Parsed: false, File: false, Value: tcase.Raw}
+
+			err := p.Parse()
+			if err != nil {
+				t.Errorf("unexpected error: <%s>", err)
+				t.FailNow()
+			}
+
+			if !p.Parsed {
+				t.Errorf("expected parameter to be parsed")
+				t.FailNow()
+			}
+
+			cast, canCast := p.Value.(bool)
+			if !canCast {
+				t.Errorf("expected parameter to be a bool")
+				t.FailNow()
+			}
+
+			if cast != tcase.BoolValue {
+				t.Errorf("expected a value of %t, got %t", tcase.BoolValue, cast)
+				t.FailNow()
+			}
+		})
+	}
+
+}
+
+func TestJsonPrimitiveFloat(t *testing.T) {
+	tcases := []struct {
+		Raw        string
+		FloatValue float64
+	}{
+		{"1", 1},
+		{"-1", -1},
+
+		{"0.001", 0.001},
+		{"-0.001", -0.001},
+
+		{"1.9992", 1.9992},
+		{"-1.9992", -1.9992},
+
+		{"19992", 19992},
+		{"-19992", -19992},
+	}
+
+	for i, tcase := range tcases {
+		t.Run("case "+string(i), func(t *testing.T) {
+			p := Parameter{Parsed: false, File: false, Value: tcase.Raw}
+
+			err := p.Parse()
+			if err != nil {
+				t.Errorf("unexpected error: <%s>", err)
+				t.FailNow()
+			}
+
+			if !p.Parsed {
+				t.Errorf("expected parameter to be parsed")
+				t.FailNow()
+			}
+
+			cast, canCast := p.Value.(float64)
+			if !canCast {
+				t.Errorf("expected parameter to be a float64")
+				t.FailNow()
+			}
+
+			if math.Abs(cast-tcase.FloatValue) > 0.00001 {
+				t.Errorf("expected a value of %f, got %f", tcase.FloatValue, cast)
+				t.FailNow()
+			}
+		})
+	}
+
+}
+
+func TestJsonBoolSlice(t *testing.T) {
+	p := Parameter{Parsed: false, File: false, Value: []string{"true", "false"}}
+
+	err := p.Parse()
+
+	if err != nil {
+		t.Errorf("unexpected error: <%s>", err)
+		t.FailNow()
+	}
+
+	if !p.Parsed {
+		t.Errorf("expected parameter to be parsed")
+		t.FailNow()
+	}
+
+	slice, canCast := p.Value.([]interface{})
+	if !canCast {
+		t.Errorf("expected parameter to be a []interface{}")
+		t.FailNow()
+	}
+
+	if len(slice) != 2 {
+		t.Errorf("expected 2 values, got %d", len(slice))
+		t.FailNow()
+	}
+
+	results := []bool{true, false}
+
+	for i, res := range results {
+
+		cast, canCast := slice[i].(bool)
+		if !canCast {
+			t.Errorf("expected parameter %d to be a []bool", i)
+			continue
+		}
+		if cast != res {
+			t.Errorf("expected first value to be '%t', got '%t'", res, cast)
+			continue
+		}
+
+	}
+
+}
+
+func TestBoolSlice(t *testing.T) {
+	p := Parameter{Parsed: false, File: false, Value: []bool{true, false}}
+
+	err := p.Parse()
+
+	if err != nil {
+		t.Errorf("unexpected error: <%s>", err)
+		t.FailNow()
+	}
+
+	if !p.Parsed {
+		t.Errorf("expected parameter to be parsed")
+		t.FailNow()
+	}
+
+	slice, canCast := p.Value.([]interface{})
+	if !canCast {
+		t.Errorf("expected parameter to be a []interface{}")
+		t.FailNow()
+	}
+
+	if len(slice) != 2 {
+		t.Errorf("expected 2 values, got %d", len(slice))
+		t.FailNow()
+	}
+
+	results := []bool{true, false}
+
+	for i, res := range results {
+
+		cast, canCast := slice[i].(bool)
+		if !canCast {
+			t.Errorf("expected parameter %d to be a bool, got %v", i, slice[i])
+			continue
+		}
+		if cast != res {
+			t.Errorf("expected first value to be '%t', got '%t'", res, cast)
+			continue
+		}
+
+	}
+
+}
diff --git a/internal/reqdata/store_test.go b/internal/reqdata/store_test.go
index 6866a8f..0805b84 100644
--- a/internal/reqdata/store_test.go
+++ b/internal/reqdata/store_test.go
@@ -1,11 +1,12 @@
 package reqdata
 
 import (
-	"bytes"
 	"fmt"
 	"net/http"
 	"net/http/httptest"
+	"net/url"
 	"reflect"
+	"strings"
 	"testing"
 )
 
@@ -222,7 +223,28 @@ func TestStoreWithGet(t *testing.T) {
 	}
 
 }
+func TestStoreWithUrlEncodedFormParseError(t *testing.T) {
+	// http.Request.ParseForm() fails when:
+	// - http.Request.Method is one of [POST,PUT,PATCH]
+	// - http.Request.Form     is not nil (created manually)
+	// - http.Request.PostForm is nil (deleted manually)
+	// - http.Request.Body     is nil (deleted manually)
 
+	req := httptest.NewRequest(http.MethodPost, "http://host.com/", nil)
+	req.Header.Add("Content-Type", "application/x-www-form-urlencoded")
+
+	// break everything
+	req.Body = nil
+	req.Form = make(url.Values)
+	req.PostForm = nil
+
+	// defer req.Body.Close()
+	store := New(nil, req)
+	if len(store.Form) > 0 {
+		t.Errorf("expected malformed urlencoded to have failed being parsed (got %d elements)", len(store.Form))
+		t.FailNow()
+	}
+}
 func TestStoreWithUrlEncodedForm(t *testing.T) {
 	tests := []struct {
 		URLEncoded string
@@ -301,7 +323,7 @@ func TestStoreWithUrlEncodedForm(t *testing.T) {
 
 	for i, test := range tests {
 		t.Run(fmt.Sprintf("request.%d", i), func(t *testing.T) {
-			body := bytes.NewBufferString(test.URLEncoded)
+			body := strings.NewReader(test.URLEncoded)
 			req := httptest.NewRequest(http.MethodPost, "http://host.com", body)
 			req.Header.Add("Content-Type", "application/x-www-form-urlencoded")
 			defer req.Body.Close()
@@ -474,7 +496,7 @@ func TestJsonParameters(t *testing.T) {
 
 	for i, test := range tests {
 		t.Run(fmt.Sprintf("request.%d", i), func(t *testing.T) {
-			body := bytes.NewBufferString(test.RawJson)
+			body := strings.NewReader(test.RawJson)
 			req := httptest.NewRequest(http.MethodPost, "http://host.com", body)
 			req.Header.Add("Content-Type", "application/json")
 			defer req.Body.Close()
@@ -545,3 +567,238 @@ func TestJsonParameters(t *testing.T) {
 	}
 
 }
+
+func TestMultipartParameters(t *testing.T) {
+	tests := []struct {
+		RawMultipart string
+
+		InvalidNames []string
+		ParamNames   []string
+		ParamValues  []interface{}
+	}{
+		// no need to fully check json because it is parsed with the standard library
+		{
+			RawMultipart: ``,
+			InvalidNames: []string{},
+			ParamNames:   []string{},
+			ParamValues:  []interface{}{},
+		},
+		{
+			RawMultipart: `--xxx
+			`,
+			InvalidNames: []string{},
+			ParamNames:   []string{},
+			ParamValues:  []interface{}{},
+		},
+		{
+			RawMultipart: `--xxx
+--xxx--`,
+			InvalidNames: []string{},
+			ParamNames:   []string{},
+			ParamValues:  []interface{}{},
+		},
+		{
+			RawMultipart: `--xxx
+Content-Disposition: form-data; name="a"
+
+b
+--xxx--`,
+			InvalidNames: []string{},
+			ParamNames:   []string{"a"},
+			ParamValues:  []interface{}{"b"},
+		},
+		{
+			RawMultipart: `--xxx
+Content-Disposition: form-data; name="a"
+
+b
+--xxx
+Content-Disposition: form-data; name="c"
+
+d
+--xxx--`,
+			InvalidNames: []string{},
+			ParamNames:   []string{"a", "c"},
+			ParamValues:  []interface{}{"b", "d"},
+		},
+		{
+			RawMultipart: `--xxx
+Content-Disposition: form-data; name="_invalid"
+
+x
+--xxx--`,
+			InvalidNames: []string{"_invalid"},
+			ParamNames:   []string{"_invalid"},
+			ParamValues:  []interface{}{nil},
+		},
+		{
+			RawMultipart: `--xxx
+Content-Disposition: form-data; name="a"
+
+b
+--xxx
+Content-Disposition: form-data; name="_invalid"
+
+x
+--xxx--`,
+			InvalidNames: []string{"_invalid"},
+			ParamNames:   []string{"a", "_invalid"},
+			ParamValues:  []interface{}{"b", nil},
+		},
+
+		{
+			RawMultipart: `--xxx
+Content-Disposition: form-data; name="invalid_"
+
+x
+--xxx--`,
+			InvalidNames: []string{"invalid_"},
+			ParamNames:   []string{"invalid_"},
+			ParamValues:  []interface{}{nil},
+		},
+		{
+			RawMultipart: `--xxx
+Content-Disposition: form-data; name="a"
+
+b
+--xxx
+Content-Disposition: form-data; name="invalid_"
+
+x
+--xxx--`,
+			InvalidNames: []string{"invalid_"},
+			ParamNames:   []string{"a", "invalid_"},
+			ParamValues:  []interface{}{"b", nil},
+		},
+
+		{
+			RawMultipart: `--xxx
+Content-Disposition: form-data; name="GET@injection"
+
+x
+--xxx--`,
+			InvalidNames: []string{"GET@injection"},
+			ParamNames:   []string{"GET@injection"},
+			ParamValues:  []interface{}{nil},
+		},
+		{
+			RawMultipart: `--xxx
+Content-Disposition: form-data; name="a"
+
+b
+--xxx
+Content-Disposition: form-data; name="GET@injection"
+
+x
+--xxx--`,
+			InvalidNames: []string{"GET@injection"},
+			ParamNames:   []string{"a", "GET@injection"},
+			ParamValues:  []interface{}{"b", nil},
+		},
+
+		{
+			RawMultipart: `--xxx
+Content-Disposition: form-data; name="URL#injection"
+
+x
+--xxx--`,
+			InvalidNames: []string{"URL#injection"},
+			ParamNames:   []string{"URL#injection"},
+			ParamValues:  []interface{}{nil},
+		},
+		{
+			RawMultipart: `--xxx
+Content-Disposition: form-data; name="a"
+
+b
+--xxx
+Content-Disposition: form-data; name="URL#injection"
+
+x
+--xxx--`,
+			InvalidNames: []string{"URL#injection"},
+			ParamNames:   []string{"a", "URL#injection"},
+			ParamValues:  []interface{}{"b", nil},
+		},
+		// json parse error
+		{
+			RawMultipart: "{ \"a\": \"b\", }",
+			InvalidNames: []string{},
+			ParamNames:   []string{},
+			ParamValues:  []interface{}{},
+		},
+	}
+
+	for i, test := range tests {
+		t.Run(fmt.Sprintf("request.%d", i), func(t *testing.T) {
+			body := strings.NewReader(test.RawMultipart)
+			req := httptest.NewRequest(http.MethodPost, "http://host.com", body)
+			req.Header.Add("Content-Type", "multipart/form-data; boundary=xxx")
+			defer req.Body.Close()
+			store := New(nil, req)
+
+			if test.ParamNames == nil || test.ParamValues == nil {
+				if len(store.Set) != 0 {
+					t.Errorf("expected no JSON parameters and got %d", len(store.Get))
+					t.Failed()
+				}
+
+				// no param to check
+				return
+			}
+
+			if len(test.ParamNames) != len(test.ParamValues) {
+				t.Errorf("invalid test: names and values differ in size (%d vs %d)", len(test.ParamNames), len(test.ParamValues))
+				t.Failed()
+			}
+
+			for pi, pName := range test.ParamNames {
+				key := pName
+				value := test.ParamValues[pi]
+
+				isNameValid := true
+				for _, invalid := range test.InvalidNames {
+					if pName == invalid {
+						isNameValid = false
+					}
+				}
+
+				t.Run(key, func(t *testing.T) {
+
+					param, isset := store.Set[key]
+					if !isset {
+						if isNameValid {
+							t.Errorf("store should contain element with key '%s'", key)
+							t.Failed()
+						}
+						return
+					}
+
+					// if should be invalid
+					if isset && !isNameValid {
+						t.Errorf("store should NOT contain element with key '%s' (invalid name)", key)
+						t.Failed()
+					}
+
+					valueType := reflect.TypeOf(value)
+
+					paramValue := param.Value
+					paramValueType := reflect.TypeOf(param.Value)
+
+					if valueType != paramValueType {
+						t.Errorf("should be of type %v (got '%v')", valueType, paramValueType)
+						t.Failed()
+					}
+
+					if paramValue != value {
+						t.Errorf("should return %v (got '%v')", value, paramValue)
+						t.Failed()
+					}
+
+				})
+
+			}
+		})
+	}
+
+}
diff --git a/typecheck/builtin/string_test.go b/typecheck/builtin/string_test.go
index 048485b..d23b7bf 100644
--- a/typecheck/builtin/string_test.go
+++ b/typecheck/builtin/string_test.go
@@ -41,6 +41,18 @@ func TestString_AvailableTypes(t *testing.T) {
 		{"string(1 )", false},
 		{"string( 1 )", false},
 
+		{"string()", false},
+		{"string(a)", false},
+		{"string(-1)", false},
+
+		{"string(,)", false},
+		{"string(1,b)", false},
+		{"string(a,b)", false},
+		{"string(a,1)", false},
+		{"string(-1,1)", false},
+		{"string(1,-1)", false},
+		{"string(-1,-1)", false},
+
 		{"string(1,2)", true},
 		{"string(1, 2)", true},
 		{"string(1,  2)", false},
diff --git a/typecheck/builtin/uint_test.go b/typecheck/builtin/uint_test.go
index c1d26aa..4a6ceb8 100644
--- a/typecheck/builtin/uint_test.go
+++ b/typecheck/builtin/uint_test.go
@@ -96,6 +96,11 @@ func TestUint_Values(t *testing.T) {
 		// strane offset because of how precision works
 		{fmt.Sprintf("%f", float64(math.MaxUint64+1024*3)), false},
 
+		{[]byte(fmt.Sprintf("%d", math.MaxInt64)), true},
+		{[]byte(fmt.Sprintf("%d", uint(math.MaxUint64))), true},
+		// strane offset because of how precision works
+		{[]byte(fmt.Sprintf("%f", float64(math.MaxUint64+1024*3))), false},
+
 		{"string", false},
 		{[]byte("bytes"), false},
 		{-0.1, false},