Privacy Policy

Last updated 30 September 2026

Tachyn turns your voice into text. This policy explains what that involves, in plain terms.

1. Who we are

Tachyn is provided by Sylphx Limited, registered in England and Wales, company no. 16438428 (registered office: 128 City Road, London EC1V 2NX; phone +44 7537 188 188) ("we", "us"). We are the controller of the personal data described here. Contact us about anything in this policy at hi@tachyn.ai.

2. What we process

Account: the email address and account identifier from your Tachyn sign-in.
Early-access list: if you ask for the Mac build on the website, the email address you give, the page you were on and the notice you accepted. If you also tick the optional ad-measurement box, the ad click ID from your visit's address and the time you ticked it.
Audio: while you hold the dictation key, your voice is streamed to our servers and on to a speech recognition provider to turn it into text. It is processed as it arrives and is not stored by us.
Request context: to recognise names and jargon, a request can carry your personal vocabulary, the name of the app you are typing in, the window title and the text just before the cursor. It is used for that request only and is not stored by us.
Text clean-up: recognised text may be sent to a language model to remove fillers and add punctuation. It is not stored by us, and the model provider is asked not to store it.
Transcripts and history: these stay on your Mac. They are not uploaded to us.
Download requests: if you ask on the download page to be emailed the macOS build, your email address, the notice you accepted and the time you accepted it. We use it only to send you the download link.
Usage counts: for each dictation, the number of words and seconds of audio, and the day. This is how we apply the free allowance and fair use. It contains no content.
Billing: if you subscribe, Stripe collects your name, email, card details and billing country. We receive your plan, subscription status and a Stripe customer reference; we never see your full card number.
Service logs: account identifier, request type, duration, word count and result, to run and secure the service. Logs never contain audio or text.

3. Why, and our legal basis

To provide the service you asked for (performance of our contract with you): recognition, clean-up, your plan and allowance, and billing.
To run, secure and improve the service, apply fair use, and detect and prevent abuse and fraud, using usage counts and logs that contain no audio or text (our legitimate interests).
To tell customers about Tachyn's features and offers by email, which you can stop at any time (our legitimate interests).
To establish, exercise or defend legal claims, and as part of any sale or reorganisation of our business (our legitimate interests).
To keep tax and accounting records (legal obligation).

We do not sell your data, and we do not use your audio or text to train models.

4. Who helps us (subprocessors)

Sylphx AI, the speech and model gateway operated by Sylphx Limited, which passes each request to the provider below and does not keep audio or text.
Soniox, Inc. (United States): realtime speech recognition.
OpenAI, L.L.C. (United States): speech recognition for finished audio and as a fallback.
Alibaba Cloud (Qwen models): text clean-up.
Stripe Payments Europe, Ltd. and Stripe, Inc.: payments, invoices, tax calculation and the customer portal.
Google LLC (United States): Google Analytics receives the one sign-up event described under The website, only if you opted in.
Hetzner Online GmbH (Germany): the servers our service runs on.

These are the providers we use today. We may change them, and we keep this list current.

Where data goes outside the UK, it is protected by UK adequacy regulations, the UK Extension to the EU-US Data Privacy Framework, or the UK International Data Transfer Addendum, as applicable.

5. How long we keep it

Audio, request context and clean-up text: not kept once the request ends.
Usage counts and service logs: for a limited period, then deleted automatically.
Early-access list: until we have sent you the Mac build or you ask us to remove you. The ad click ID, if you opted in: until you withdraw consent, and at most 90 days.
Account and plan: while your account exists; deleted when you delete your account in the app (Settings, Account, Delete account; cancel any subscription first) or ask us to.
Billing and tax records: as long as tax and company law requires. Stripe keeps its own records under its privacy policy.

We may keep what we need to establish or defend legal claims, or to prevent abuse and fraud, for as long as that need lasts.

6. Your rights

Under UK GDPR you can ask us for a copy of your data, to correct it, to delete it, to restrict or object to how we use it, and to receive it in a portable form. These rights have conditions and exceptions set by law. Email hi@tachyn.ai from your account's email address. We reply within one month, which the law lets us extend by two further months for complex or numerous requests; we search as far as is reasonable and proportionate, and we may charge a reasonable fee for, or refuse, a request that is manifestly unfounded or excessive.

Your right to object: where we rely on our legitimate interests, you can object to our use of your data on grounds relating to your situation, and we stop unless we have compelling legitimate grounds or need it for a legal claim. You can object to direct marketing at any time, and we then stop.

If you are unhappy with how we handle your data, you can complain to the Information Commissioner's Office (ICO), the UK data protection regulator: ico.org.uk, telephone 0303 123 1113. We would appreciate the chance to put things right first.

7. Security

We protect your data with measures suited to the risk. By design, connections are encrypted in transit, no provider keys are held on your device, every request is checked against your signed-in account, and no audio or text is kept on disk. No system is completely secure. If a breach puts your rights at high risk, we tell you as the law requires.

8. Children

Tachyn is not intended for children under 13, and we do not knowingly collect their data. If we learn that an account belongs to a child under 13, we may close it.

9. The website

This website sets no cookies, runs no scripts and loads nothing from analytics or advertising companies. Our web server records standard request logs (address, page including any ad click ID in the web address, time) for security, kept for a limited period.

Ad measurement is optional and off unless you tick the box on the early-access form. If you tick it, our server (not your browser) keeps the ad click ID from your visit's address with your request and sends Google Analytics one event saying that a sign-up happened, with a random number that is new for each sign-up. We send Google no email address, name, IP address or browser details. We use this only to see which ads lead to sign-ups, on the basis of your consent, which you can withdraw at any time by emailing us, and we then delete the stored click ID. Google handles that event under its own privacy policy.

Signing in at accounts.tachyn.ai sets one strictly necessary session cookie for that address only; if you choose Continue with Google, Google processes your sign-in under its own policy.

If you reach us from Tryit (tryit.fun), the web address carries an anonymous Tryit reference number. Our server keeps it with your early-access request, and tells Tryit, with that number alone, that a sign-up happened so Tryit can credit the visit. No email address, name or IP address goes to Tryit.

10. Changes

We may update this policy and post the new version here with its date. If we plan to use your data for a new purpose, we tell you in the app or by email before we do.