PromptVEX
Claude·fal.ai·Kling·Runway

Test your video prompts
before you waste a render.

PromptVEX scores your prompt with Claude, renders a 4-frame keyframe storyboard instantly, and only routes to a full generation once it's ready. Stop wasting full-quality runs to find out a phrase was ambiguous.

No credit card · Cancel anytime · Subscription only
live demo · no signup
aspect 16:9|duration 5s|seed 84219
34 tokens · est. quality 8.4/10
Last analysis: subject clear · motion specific · style ambiguous (consider adding an era reference)
02 — workflow

A loop, not a shotgun.

Three stages, scoped to cost. Each one filters out the next, so the expensive call is the last one you make.
01

Instant prompt scoring

Claude grades your prompt across motion, style, subject, lighting and camera language. You get a numeric score and 3 concrete rewrites — in under 2s.

  • Free, unlimited
  • Heuristics + LLM combined
  • Side-by-side rewrite diff
02

Cheap draft previews

Generate a 4-frame keyframe storyboard via fal.ai SDXL. Or a 5-second 480p draft video. See if the vibe lands before routing to full gen.

  • Fast keyframe storyboard
  • 5s 480p draft preview
  • Compare up to 4 seeds
03

Route to full gen

Once the prompt scores 80+ and the draft looks right, PromptVEX picks Kling, Runway or Veo based on your prompt's motion profile and budget.

  • Auto model selection
  • Cost estimator
  • One-click re-route
68%
avg. quota saved vs. unscored generation
12,400+
prompts analyzed last week
2.1s
median scoring latency
4
video models routed end-to-end

Stop guessing. Start scoring.

2 free videos when you sign up. Subscribe to unlock unlimited prompt analysis and full-gen routing.