Lightweight Web-Based Puzzle Config Tester (HTML + JavaScript)

I need a simple web interface I can open in my iPhone’s browser to test puzzle .json files. Features required:
• Load .json from a folder or upload
• Display game data or run simple logic (e.g. tap grid, memory pattern)
• Minimal UI: a dropdown or load button to pick a game
• Work offline or hosted via PlayCanvas, Firebase, or static file hosting
• I’ll upload the game files myself; developer only builds the wrapper

Please show me simple examples of similar HTML/JS work.