diff --git a/encoders/filter/filter.go b/encoders/filter/filter.go
index bb517a9..f77ff65 100644
--- a/encoders/filter/filter.go
+++ b/encoders/filter/filter.go
@@ -37,6 +37,12 @@ type F struct {
 	Until   *timestamp.T `json:"until,omitempty"`
 	Search  []byte       `json:"search,omitempty"`
 	Limit   *uint        `json:"limit,omitempty"`
+
+	// Extra holds unknown JSON fields for relay extensions (e.g., _graph).
+	// Per NIP-01, unknown fields should be ignored by relays that don't support them,
+	// but relays implementing extensions can access them here.
+	// Keys are stored without quotes, values are raw JSON bytes.
+	Extra map[string][]byte `json:"-"`
 }
 
 // New creates a new, reasonably initialized filter that will be ready for most uses without
@@ -510,7 +516,18 @@ func (f *F) Unmarshal(b []byte) (r []byte, err error) {
 					// log.I.Ln("betweenKV")
 				}
 			default:
-				goto invalid
+				// Per NIP-01, unknown filter fields should be ignored by relays that
+				// don't support them. Store them in Extra for extensions to use.
+				var val []byte
+				if val, r, err = skipJSONValue(r); err != nil {
+					goto invalid
+				}
+				if f.Extra == nil {
+					f.Extra = make(map[string][]byte)
+				}
+				// Store the raw JSON value keyed by the field name
+				f.Extra[string(key)] = val
+				state = betweenKV
 			}
 			key = key[:0]
 		case betweenKV:
diff --git a/encoders/filter/skip.go b/encoders/filter/skip.go
new file mode 100644
index 0000000..6354ad9
--- /dev/null
+++ b/encoders/filter/skip.go
@@ -0,0 +1,161 @@
+package filter
+
+import (
+	"lol.mleku.dev/errorf"
+)
+
+// skipJSONValue skips over an arbitrary JSON value and returns the raw bytes and remainder.
+// It handles: objects {}, arrays [], strings "", numbers, true, false, null.
+// The input `b` should start at the first character of the value (after the colon in "key":value).
+func skipJSONValue(b []byte) (val []byte, r []byte, err error) {
+	if len(b) == 0 {
+		err = errorf.E("empty input")
+		return
+	}
+
+	start := 0
+	end := 0
+
+	switch b[0] {
+	case '{':
+		// Object - find matching closing brace
+		end, err = findMatchingBrace(b, '{', '}')
+	case '[':
+		// Array - find matching closing bracket
+		end, err = findMatchingBrace(b, '[', ']')
+	case '"':
+		// String - find closing quote (handling escapes)
+		end, err = findClosingQuote(b)
+	case 't':
+		// true
+		if len(b) >= 4 && string(b[:4]) == "true" {
+			end = 4
+		} else {
+			err = errorf.E("invalid JSON value starting with 't'")
+		}
+	case 'f':
+		// false
+		if len(b) >= 5 && string(b[:5]) == "false" {
+			end = 5
+		} else {
+			err = errorf.E("invalid JSON value starting with 'f'")
+		}
+	case 'n':
+		// null
+		if len(b) >= 4 && string(b[:4]) == "null" {
+			end = 4
+		} else {
+			err = errorf.E("invalid JSON value starting with 'n'")
+		}
+	case '-', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
+		// Number - scan until we hit a non-number character
+		end = scanNumber(b)
+	default:
+		err = errorf.E("invalid JSON value starting with '%c'", b[0])
+	}
+
+	if err != nil {
+		return
+	}
+
+	val = b[start:end]
+	r = b[end:]
+	return
+}
+
+// findMatchingBrace finds the index after the closing brace/bracket that matches the opening one.
+// It handles nested structures and strings.
+func findMatchingBrace(b []byte, open, close byte) (end int, err error) {
+	if len(b) == 0 || b[0] != open {
+		err = errorf.E("expected '%c'", open)
+		return
+	}
+
+	depth := 0
+	inString := false
+	escaped := false
+
+	for i := 0; i < len(b); i++ {
+		c := b[i]
+
+		if escaped {
+			escaped = false
+			continue
+		}
+
+		if c == '\\' && inString {
+			escaped = true
+			continue
+		}
+
+		if c == '"' {
+			inString = !inString
+			continue
+		}
+
+		if inString {
+			continue
+		}
+
+		if c == open {
+			depth++
+		} else if c == close {
+			depth--
+			if depth == 0 {
+				end = i + 1
+				return
+			}
+		}
+	}
+
+	err = errorf.E("unmatched '%c'", open)
+	return
+}
+
+// findClosingQuote finds the index after the closing quote of a JSON string.
+// Handles escape sequences.
+func findClosingQuote(b []byte) (end int, err error) {
+	if len(b) == 0 || b[0] != '"' {
+		err = errorf.E("expected '\"'")
+		return
+	}
+
+	escaped := false
+	for i := 1; i < len(b); i++ {
+		c := b[i]
+
+		if escaped {
+			escaped = false
+			continue
+		}
+
+		if c == '\\' {
+			escaped = true
+			continue
+		}
+
+		if c == '"' {
+			end = i + 1
+			return
+		}
+	}
+
+	err = errorf.E("unclosed string")
+	return
+}
+
+// scanNumber scans a JSON number and returns the index after it.
+// Handles integers, decimals, and scientific notation.
+func scanNumber(b []byte) (end int) {
+	for i := 0; i < len(b); i++ {
+		c := b[i]
+		// Number characters: digits, minus, plus, dot, e, E
+		if (c >= '0' && c <= '9') || c == '-' || c == '+' || c == '.' || c == 'e' || c == 'E' {
+			continue
+		}
+		end = i
+		return
+	}
+	end = len(b)
+	return
+}
diff --git a/encoders/filter/skip_test.go b/encoders/filter/skip_test.go
new file mode 100644
index 0000000..9d3bbdc
--- /dev/null
+++ b/encoders/filter/skip_test.go
@@ -0,0 +1,339 @@
+package filter
+
+import (
+	"testing"
+)
+
+func TestSkipJSONValue(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		wantVal  string
+		wantRem  string
+		wantErr  bool
+	}{
+		// Objects
+		{
+			name:    "empty object",
+			input:   `{}`,
+			wantVal: `{}`,
+			wantRem: "",
+		},
+		{
+			name:    "simple object",
+			input:   `{"foo":"bar"}`,
+			wantVal: `{"foo":"bar"}`,
+			wantRem: "",
+		},
+		{
+			name:    "nested object",
+			input:   `{"a":{"b":"c"}},"next"`,
+			wantVal: `{"a":{"b":"c"}}`,
+			wantRem: `,"next"`,
+		},
+		{
+			name:    "object with array",
+			input:   `{"items":[1,2,3]}rest`,
+			wantVal: `{"items":[1,2,3]}`,
+			wantRem: `rest`,
+		},
+
+		// Arrays
+		{
+			name:    "empty array",
+			input:   `[]`,
+			wantVal: `[]`,
+			wantRem: "",
+		},
+		{
+			name:    "number array",
+			input:   `[1,2,3]`,
+			wantVal: `[1,2,3]`,
+			wantRem: "",
+		},
+		{
+			name:    "string array",
+			input:   `["a","b","c"],rest`,
+			wantVal: `["a","b","c"]`,
+			wantRem: `,rest`,
+		},
+		{
+			name:    "nested array",
+			input:   `[[1,2],[3,4]]more`,
+			wantVal: `[[1,2],[3,4]]`,
+			wantRem: `more`,
+		},
+
+		// Strings
+		{
+			name:    "simple string",
+			input:   `"hello"`,
+			wantVal: `"hello"`,
+			wantRem: "",
+		},
+		{
+			name:    "string with escapes",
+			input:   `"hello \"world\""rest`,
+			wantVal: `"hello \"world\""`,
+			wantRem: `rest`,
+		},
+		{
+			name:    "string with backslash",
+			input:   `"path\\to\\file",next`,
+			wantVal: `"path\\to\\file"`,
+			wantRem: `,next`,
+		},
+
+		// Numbers
+		{
+			name:    "integer",
+			input:   `123`,
+			wantVal: `123`,
+			wantRem: "",
+		},
+		{
+			name:    "negative integer",
+			input:   `-456,next`,
+			wantVal: `-456`,
+			wantRem: `,next`,
+		},
+		{
+			name:    "decimal",
+			input:   `3.14159}`,
+			wantVal: `3.14159`,
+			wantRem: `}`,
+		},
+		{
+			name:    "scientific notation",
+			input:   `1.23e-4,next`,
+			wantVal: `1.23e-4`,
+			wantRem: `,next`,
+		},
+
+		// Booleans
+		{
+			name:    "true",
+			input:   `true`,
+			wantVal: `true`,
+			wantRem: "",
+		},
+		{
+			name:    "false",
+			input:   `false,next`,
+			wantVal: `false`,
+			wantRem: `,next`,
+		},
+
+		// Null
+		{
+			name:    "null",
+			input:   `null`,
+			wantVal: `null`,
+			wantRem: "",
+		},
+		{
+			name:    "null with remainder",
+			input:   `null}`,
+			wantVal: `null`,
+			wantRem: `}`,
+		},
+
+		// Complex nested structures
+		{
+			name:    "graph query object",
+			input:   `{"method":"follows","seed":"abc123","depth":2,"inbound_refs":[{"kinds":[7],"from_depth":1}]},rest`,
+			wantVal: `{"method":"follows","seed":"abc123","depth":2,"inbound_refs":[{"kinds":[7],"from_depth":1}]}`,
+			wantRem: `,rest`,
+		},
+
+		// Error cases
+		{
+			name:    "empty input",
+			input:   ``,
+			wantErr: true,
+		},
+		{
+			name:    "unclosed object",
+			input:   `{"foo":"bar"`,
+			wantErr: true,
+		},
+		{
+			name:    "unclosed array",
+			input:   `[1,2,3`,
+			wantErr: true,
+		},
+		{
+			name:    "unclosed string",
+			input:   `"hello`,
+			wantErr: true,
+		},
+		{
+			name:    "invalid true",
+			input:   `tru`,
+			wantErr: true,
+		},
+		{
+			name:    "invalid false",
+			input:   `fals`,
+			wantErr: true,
+		},
+		{
+			name:    "invalid null",
+			input:   `nul`,
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			val, rem, err := skipJSONValue([]byte(tt.input))
+
+			if tt.wantErr {
+				if err == nil {
+					t.Errorf("expected error, got nil")
+				}
+				return
+			}
+
+			if err != nil {
+				t.Errorf("unexpected error: %v", err)
+				return
+			}
+
+			if string(val) != tt.wantVal {
+				t.Errorf("val = %q, want %q", string(val), tt.wantVal)
+			}
+
+			if string(rem) != tt.wantRem {
+				t.Errorf("rem = %q, want %q", string(rem), tt.wantRem)
+			}
+		})
+	}
+}
+
+func TestUnmarshalWithUnknownFields(t *testing.T) {
+	tests := []struct {
+		name       string
+		input      string
+		wantKinds  []int
+		wantExtra  map[string]string
+		wantErr    bool
+	}{
+		{
+			name:      "simple filter with _graph extension",
+			input:     `{"kinds":[1,7],"_graph":{"method":"follows","seed":"abc123","depth":2}}`,
+			wantKinds: []int{1, 7},
+			wantExtra: map[string]string{
+				"_graph": `{"method":"follows","seed":"abc123","depth":2}`,
+			},
+		},
+		{
+			name:      "filter with unknown string field",
+			input:     `{"kinds":[1],"_custom":"value"}`,
+			wantKinds: []int{1},
+			wantExtra: map[string]string{
+				"_custom": `"value"`,
+			},
+		},
+		{
+			name:      "filter with multiple unknown fields",
+			input:     `{"kinds":[1],"_foo":123,"_bar":["a","b"]}`,
+			wantKinds: []int{1},
+			wantExtra: map[string]string{
+				"_foo": `123`,
+				"_bar": `["a","b"]`,
+			},
+		},
+		{
+			name:      "filter with complex _graph extension",
+			input:     `{"kinds":[0],"_graph":{"method":"follows","seed":"abc","depth":2,"inbound_refs":[{"kinds":[7],"from_depth":1}]}}`,
+			wantKinds: []int{0},
+			wantExtra: map[string]string{
+				"_graph": `{"method":"follows","seed":"abc","depth":2,"inbound_refs":[{"kinds":[7],"from_depth":1}]}`,
+			},
+		},
+		{
+			name:      "unknown field before known fields",
+			input:     `{"_unknown":true,"kinds":[3]}`,
+			wantKinds: []int{3},
+			wantExtra: map[string]string{
+				"_unknown": `true`,
+			},
+		},
+		{
+			name:      "unknown field with null value",
+			input:     `{"kinds":[1],"_nullable":null}`,
+			wantKinds: []int{1},
+			wantExtra: map[string]string{
+				"_nullable": `null`,
+			},
+		},
+		{
+			name:      "standard filter without unknown fields",
+			input:     `{"kinds":[1,7]}`,
+			wantKinds: []int{1, 7},
+			wantExtra: nil,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			f := &F{}
+			_, err := f.Unmarshal([]byte(tt.input))
+
+			if tt.wantErr {
+				if err == nil {
+					t.Errorf("expected error, got nil")
+				}
+				return
+			}
+
+			if err != nil {
+				t.Errorf("unexpected error: %v", err)
+				return
+			}
+
+			// Check kinds
+			if f.Kinds != nil {
+				if f.Kinds.Len() != len(tt.wantKinds) {
+					t.Errorf("kinds len = %d, want %d", f.Kinds.Len(), len(tt.wantKinds))
+				} else {
+					for i, k := range f.Kinds.K {
+						if int(k.K) != tt.wantKinds[i] {
+							t.Errorf("kinds[%d] = %d, want %d", i, k.K, tt.wantKinds[i])
+						}
+					}
+				}
+			} else if len(tt.wantKinds) > 0 {
+				t.Errorf("kinds is nil, want %v", tt.wantKinds)
+			}
+
+			// Check extra fields
+			if tt.wantExtra == nil {
+				if f.Extra != nil && len(f.Extra) > 0 {
+					t.Errorf("extra = %v, want nil", f.Extra)
+				}
+			} else {
+				if f.Extra == nil {
+					t.Errorf("extra is nil, want %v", tt.wantExtra)
+					return
+				}
+				for key, wantVal := range tt.wantExtra {
+					gotVal, ok := f.Extra[key]
+					if !ok {
+						t.Errorf("extra[%q] not found", key)
+						continue
+					}
+					if string(gotVal) != wantVal {
+						t.Errorf("extra[%q] = %q, want %q", key, string(gotVal), wantVal)
+					}
+				}
+				for key := range f.Extra {
+					if _, ok := tt.wantExtra[key]; !ok {
+						t.Errorf("unexpected extra key %q", key)
+					}
+				}
+			}
+		})
+	}
+}