Privacy Policy & Terms of Service
Last updated: August 2026
We've written this in plain English. If something isn't clear, email us at hello@halfnine.app and we'll explain it. Legal language is designed to protect us; we'd rather just be straight with you.
Who we are
Half Nine is operated by Half Nine Ltd, 66 Paul Street, London, England, United Kingdom, EC2A 4NA. We are the data controller for all personal data collected through this service.
Contact: hello@halfnine.app
Terms of Service
Using Half Nine
By signing up for Half Nine you agree to these terms. You must be at least 16 years old. Half Nine is a personal productivity tool — please don't use it for anything unlawful or harmful.
Our service
We'll do our best to deliver your check-in every evening at 9:30pm local time. We can't guarantee uninterrupted service — we depend on WhatsApp and third-party infrastructure — but we'll be transparent if something goes wrong.
Pricing
Half Nine includes a 14-day free trial. After that, a Ko-fi membership is required to continue receiving check-ins. We'll notify you 2 days before your trial ends. If your membership lapses, check-ins pause but your data is never deleted — you can export or resubscribe at any time.
Termination
You can close your account any time by messaging Half Nine "delete my account" or emailing us. We can suspend accounts that misuse the service, but we'd rather not have to.
Liability
Half Nine is a habit tracking tool, not a medical or therapeutic service. Nothing in the app constitutes health, medical, or psychological advice. We're not liable for decisions you make based on your check-in data.
Changes to these terms
If we make significant changes we'll notify you via WhatsApp before they take effect.
Privacy Policy
What we collect
- Email address — collected when you sign in via Google or Apple, and when you join the waitlist. Used to identify your account.
- WhatsApp number — collected during onboarding. Used to send your daily check-in and receive your replies.
- Goals — the fitness, diet, and lifestyle goals you set. Stored to personalise your check-in questions.
- Check-in responses — your yes/no answers each evening, the date, and your current streak.
- Notes — any free-text you add after a check-in. Optional and entirely in your own words.
- Timezone — collected during onboarding to send your check-in at 9:30pm your local time.
We do not collect location data, device identifiers, browsing history, or any data beyond what's listed above.
Why we collect it (lawful basis)
We process your data on the basis of consent — you chose to sign up for Half Nine and provide this information. You can withdraw consent at any time by deleting your account.
How we use your data
- Sending your evening check-in via WhatsApp
- Personalising your check-in questions with your goals
- Calculating your streak and displaying your progress
- Generating your weekly summary image
- Automatically tagging your notes with themes (see AI section below)
- Sending you a monthly goals review
We do not use your data for advertising, profiling, or any purpose beyond delivering the Half Nine service to you.
Your WhatsApp number — our specific commitment
Your WhatsApp number is used for one thing: delivering your check-in and receiving your replies. We will never send you unsolicited messages, never use your number for marketing, and never sell or share it with any party other than Twilio (the service we use to send WhatsApp messages). If you delete your account, your number is deleted immediately.
AI and automated processing
When you write a note after a check-in, that note is automatically sent to Google Gemini (via Vertex AI) to extract short theme tags — things like "stress", "social pressure", or "good run". This helps you see patterns in your notes over time.
This processing is:
- Automated — no human at Half Nine or Google reads your notes
- Limited to note tagging only — your yes/no answers and goals are never sent to Gemini
- Governed by Google's Data Processing Agreement, which is part of their standard GCP terms
If you'd prefer your notes not to be processed by AI, don't use the note field — just reply DONE after your yes/no questions. Your check-in is just as useful without it.
Third-party processors
We share data with the following processors, solely to deliver the Half Nine service:
- Twilio — sends and receives your WhatsApp messages. Receives your WhatsApp number and the content of messages. Twilio Privacy Policy.
- Google Firebase — handles authentication (sign-in with Google/Apple) and stores your data. Firebase Privacy Policy.
- Google Cloud (Firestore) — database where your goals, check-ins, and notes are stored. Data is stored in europe-west2 (London).
- Google Vertex AI (Gemini) — processes free-text notes to generate tags. See AI section above. Google DPA.
- Google Analytics 4 — measures how people use the website and app (page views, sign-up funnel, feature usage). Does not receive your goals, check-in responses, or notes. Google Privacy Policy.
We do not use advertising networks or any other third-party services.
Where your data is stored
All data is stored on Google Cloud Platform in europe-west2 (London, UK). Your data does not leave the UK.
How long we keep your data
We keep your data for as long as your account is active. If you delete your account, all of your data — goals, check-ins, notes, your WhatsApp number — is deleted within 48 hours. We do not retain backups of deleted accounts.
Your rights under UK GDPR
You have the right to:
- Access — request a copy of all data we hold about you
- Correction — ask us to correct inaccurate data
- Deletion — ask us to delete your data ("right to be forgotten")
- Portability — receive your data in a machine-readable format
- Restriction — ask us to pause processing your data
- Objection — object to how we're using your data
- Withdraw consent — close your account at any time
To exercise any of these rights, email hello@halfnine.app. We'll respond within 30 days.
If you're unhappy with how we've handled your data, you have the right to complain to the Information Commissioner's Office (ICO).
Security
Your data is protected by:
- Encryption at rest and in transit (Google Cloud default)
- Firebase Authentication — we never store passwords
- Access controls — only the minimum data needed reaches each service
- WhatsApp number verification via one-time code to prevent unauthorised linking
No system is perfectly secure. If we ever become aware of a breach affecting your data, we'll notify you as required by UK GDPR (within 72 hours of discovery).
Children
Half Nine is not intended for anyone under 16. We don't knowingly collect data from under-16s. If you believe a child has signed up, please email us and we'll delete their account immediately.
Changes to this policy
If we make material changes to this privacy policy, we'll notify you via WhatsApp before they take effect. The "last updated" date at the top of this page will reflect the most recent version.