What it does PromptFill is a browser-based editor for AI image-generation prompts. You build reusable templates with {{variables}}, manage option banks (character styles, lighting, aspect ratios), then fill dropdowns to generate clean prompts for Midjourney, GPT-image, Nano Banana, etc. It copies the final string or exports a long JPG for sharing.

The interesting bit The “Smart Split” feature takes an existing prompt and auto-detects replaceable chunks—anything wrapped in [], 「」, or {}—then converts them into a structured template with bilingual support. It is essentially a refactoring tool for prompt spaghetti.

Key highlights

• Dual-column autocomplete: type / or { to pick a variable and its value without leaving the editor
• Linkage groups sync the same variable across multiple slots (e.g., {{color}}_1)
• Storage toggles between IndexedDB and local-folder mode without losing templates
• Optional self-hosted share server (Node.js + SQLite) for short links; falls back to long URLs offline
• Built-in AI prompt expansion and 10+ official templates (infographics, city posters, app UI mocks)

Caveats

• Data stays local by default; cross-device sync is manual JSON export/import
• Mobile disables the / autocomplete trigger to avoid soft-keyboard fights
• README warns you to back up regularly because browser storage is the default

Verdict Worth a look if you generate AI images in volume and are tired of text-file archaeology. Purely a frontend productivity tool—no model inference, no API keys required.