Building Penlify — an AI detector that shows you which sentences, not just a score

Launching Penlify on Product Hunt September 1st. Built it after getting frustrated with AI detectors that hand you one confusing percentage and stop there — you're stuck guessing which part of your draft actually triggered it.

Penlify checks sentence by sentence instead, then lets you rewrite just the flagged lines in the same workspace — no bouncing between a checker and a separate editor. Free tier is 5 rewrites and 3 detections a month, no card required.

Built mainly for students and freelancers who keep getting flagged on writing they wrote themselves. Would genuinely love feedback before launch — what would make this useful for how you actually check your own writing?