diff --git a/frontend/src/types.ts b/frontend/src/types.ts
new file mode 100644
index 0000000..2fd0e5a
--- /dev/null
+++ b/frontend/src/types.ts
@@ -0,0 +1,79 @@
+export type CellType = 'black' | 'empty'
+export type CellStatus = 'default' | 'correct' | 'incorrect' | 'revealed'
+export type Direction = 'across' | 'down'
+
+export interface ClientPuzzle {
+  width: number
+  height: number
+  cells: CellType[][]
+  clues_across: ClientClue[]
+  clues_down: ClientClue[]
+  difficulty_score: number
+  cell_numbers: Record<string, number>
+  theme?: string
+  theme_entries?: string[]
+}
+
+export interface ClientClue {
+  number: number
+  direction: string
+  text: string
+  definition?: string
+  wordplay_type?: string
+}
+
+export interface GenerateResponse {
+  id: string
+  short_id: string
+  puzzle: ClientPuzzle
+  already_solved?: boolean
+  solve_time?: number
+  solve_hints?: number
+  cell_results?: string | null
+}
+
+export interface ValidateResponse {
+  correct: boolean
+  cells: string[][]
+  rank?: number
+  percentile?: number
+  total_solvers?: number
+}
+
+export interface HintCheckResponse {
+  is_correct: boolean
+}
+
+export interface HintRevealResponse {
+  row: number
+  col: number
+  letter: string
+}
+
+export interface HintWordResponse {
+  letters: { row: number; col: number; letter: string }[]
+}
+
+export interface WordSpan {
+  number: number
+  direction: Direction
+  cells: [number, number][]
+}
+
+export type InputMode = 'keyboard' | 'stylus' | 'auto'
+export type GameMode = 'standard' | 'speedrun' | 'blind' | 'marathon'
+
+export interface StylusSettings {
+  strokeWidth: number
+  debounceMs: number
+  autoFillThreshold: number
+  ambiguityThreshold: number
+  enableOnnx: boolean
+  enableTesseract: boolean
+  enableStrokeMatcher: boolean
+}
+
+export interface RecognitionResult {
+  candidates: { letter: string; confidence: number }[]
+  cell: { row: number; col: number }
+}