Rewrite or reply to your messages before you send them, choosing from safer, funnier, or custom tones
Research-backed prompting techniques from arXiv, rated for practical value
Stage
Startup
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Founded
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Based in
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Pricing model
Freemium
Freemium
Pricing
Free: $0 forever for on-device rewrites with unlimited rewrites, no account required. Pro: $3.99/month or $39.99/year; new subscribers get a 14-day free trial and can cancel anytime.
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Key features
Safer tone that clarifies and reduces hostility
Funnier tone that changes register
Custom tone by typing your own instructions
Cloud rewrites for Pro subscribers
How I Sound feature to apply your voice to rewrites
Support for longer drafts on Pro
Works in iPhone keyboard and as an app
715 published prompting techniques scored 80+ for practical value
Scores based on practitioner applicability, evidence strength, effect size, and novelty
Copy-paste prompts for ChatGPT, Claude, and Gemini
Links to original arXiv papers for every technique
Weekly newsletter with top techniques every Sunday
Four views per technique: breakdown, plain language, digest, and role-based guides
Browsable catalog organized by technique type and publication month
No account required to access all pages and techniques
Lab score range 80-97 indicates technique quality and applicability
What makes it different
Never sends messages automatically—you always copy and send manually
Drafts never used to train models; privacy-first design
Free on-device rewrites with no daily limits or quotas
Works directly in iPhone keyboard for seamless workflow
Transparent scoring methodology with links to original papers for verification
Techniques tested across multiple models and use cases to confirm practical transferability
tono
PromptLabster