Translation. This is an English translation for your convenience. The Danish version applies; if the two differ, the Danish version prevails.

Privacy policy

Last updated: 26 October 2026

This page explains which personal data Callster processes, why, and what rights you have.

Who is responsible

Callster is operated by Callster I/S, a Danish general partnership (interessentskab) founded and owned by Max-Emil Sverker Sørensen and Mikkel Sten Gersel. CVR no. 46808266, Jægerstræde 8, 2690 Karlslunde, kontakt@callster.dk. Callster I/S is the data controller for the information described in sections 1 and 2.

For information about the people who call or write to a business that uses Callster, the business itself is the data controller, and Callster is the data processor (section 3).

1. When you visit callster.dk and try the demo

• The demo: what you write about your business, and the conversation with the demo. To create the demo, we look up your business online and use our AI and voice providers. We store neither the text nor the conversation on our side. The voice provider deletes the conversation after 30 days. The audio from the demo is not recorded.
• Waiting list: if you sign up for the waiting list, we store your email address and, if you provide it, your business's name, so that we can write to you when Callster opens.
• Misuse: to limit misuse of the demo and the waiting list, we store a one-way encoded value (hash) of your IP address together with the time. We cannot see your IP address from it.
• Sound: your choice to turn sound on or off is stored only in your own browser.
• Visitor statistics: we count visits to callster.dk anonymously with our hosting provider's statistics: which pages are seen, where the visit came from (for example a search), country and device type, and whether someone joins the waiting list. No cookies are used, and we cannot see who you are.
• We do not use cookies for advertising or tracking.

Legal basis: our legitimate interest in showing the product, measuring how the site is used and preventing misuse (GDPR Art. 6(1)(f)). The waiting list is based on your consent when you sign up (Art. 6(1)(a)). You can always withdraw it.

2. When your business is a customer

• Account: name, email address, company name, CVR number, address and telephone number.
• About the business: when you create an account, we collect information about the business from the Danish Central Business Register (CVR-registret), the business's website and searches online, so that the setup can suggest how Callster should work. You approve the suggestion before it is used.
• Payment: information for payment and invoicing. Card details are handled by our payment provider and are not stored by us.
• Owner channel: the owner's ID on the channel the owner uses to write to Callster (Messenger, Telegram or SMS), and the messages the owner sends and receives.
• Connections: keys and sessions for the systems you connect Callster to (e.g. calendar, email or point-of-sale system). They cannot be seen in the console and are used only by Callster's servers. Sessions and API keys are also stored encrypted in a separate vault. We never store your password to your own systems: you log in yourself, and we store only the session the browser receives afterwards.
• Email: if you connect your email, Callster reads the emails that are to be sorted, summarised or answered. A reply is sent only once you have said yes.
• Logs: what Callster has done and when, so that you and we can see it.

Legal basis: performance of the agreement with you (Art. 6(1)(b)) and the Danish Bookkeeping Act (bogføringsloven) for accounting information (Art. 6(1)(c)). The account information is necessary in order to use Callster. Without it, we cannot provide the service.

3. When you call or write to a business that uses Callster

Callster processes your telephone number, your name if you give it, what you are calling about, and the booking or message the conversation leads to. The conversation is stored as text with a short summary. As a rule, the audio is not recorded. If the business itself has turned on recording, the audio is stored with our voice provider and deleted after 30 days.

If you write to the business on Facebook Messenger or Instagram, and the business has set Callster up to reply there, Callster processes your message, your ID on the channel and the reply.

If you send an SMS to the business's Callster number, Callster processes your telephone number, your message and the reply, and can find your own appointment based on the number. If you write STOP, you will not receive any more SMS messages from that business via Callster until you write START.

We do this on behalf of the business you are calling or writing to. The business is the data controller. Questions about your information should therefore go to the business first, but you are also welcome to write to us.

Automated processing

Callster uses artificial intelligence to understand and respond to enquiries and to suggest replies and bookings according to the business's own rules. Callster does not make decisions about you that are based solely on automated processing and that produce legal effects concerning you or similarly significantly affect you.

Who do we share information with?

Information from a call or a message goes to the business you have contacted.

Callster uses trusted external providers for, among other things, hosting, artificial intelligence, voice, telephony and SMS, email, web search, integrations and payment processing. These providers process personal data to the extent necessary to provide the features the business uses. We use data processing agreements and security measures where required.

If you connect Callster to other services, e.g. Google, Microsoft, Meta or your own booking or point-of-sale system, Callster exchanges information with them as you have permitted. We also disclose information to authorities if required by law. If we receive such a request, we first check that it is lawful, and we challenge it if we believe it is not. We disclose only the minimum possible, and we document each request, our response and the reasoning.

We never sell personal data. Write to kontakt@callster.dk if you would like to know which providers process your information.

Transfers to countries outside the EU/EEA

Our database is located in the EU (Frankfurt). Some of our providers, including within AI, voice and telephony, process information outside the EU/EEA, particularly in the USA. When this happens, the transfer is based on a valid legal basis for transfer under the GDPR, e.g. the European Commission's adequacy decision for companies certified under the EU-US Data Privacy Framework, or the European Commission's standard contractual clauses.

You can obtain more information about the transfers and a copy of the safeguards we use by writing to kontakt@callster.dk.

Data from Meta (Facebook, Messenger and Instagram)

If the owner chooses to write to Callster on Messenger, we receive the following from Meta:

• the owner's page-scoped Messenger ID (PSID), which Meta gives us when the owner writes to the Callster page,
• the messages the owner sends to Callster, and the time.

We do not retrieve the owner's Facebook profile, friends, photos or any other information. The ID is used only to recognise the owner and send replies back. The messages are used only to carry out what the owner asks for. We do not sell them, do not use them for advertising and share them only with the providers that need them in order to deliver Callster.

If a business connects its Facebook Page or Instagram account, we receive the messages customers send to the business there, and the customer's page-scoped ID, so that Callster can reply on the business's behalf (section 3). The Page's access token is stored encrypted in a separate vault.

You can ask us to delete your data at any time. See Delete your data.

Data from Google and Microsoft

If you connect Google Calendar, Gmail or Google Sheets, Callster reads and writes only in the calendars, emails and sheets you give it access to. Callster uses the access only to see available times, create, move and cancel appointments, sort and summarise emails, write replies that are sent only once you have said yes, and read what you have asked it to. The content of the emails Callster sorts or summarises is processed by our AI provider in order to do so. The access token cannot be seen in the console and is used only by Callster's servers.

Callster's use of information received from Google APIs adheres to the Google API Services User Data Policy, including the Limited Use requirements. We do not use Google data for advertising, do not sell it and do not use it to train AI models. You can remove Gmail access in the console, and all access to your Google Account at myaccount.google.com/permissions.

If you connect Microsoft Outlook, the same applies to your Outlook email and calendar: Callster uses the access only for the same tasks. You can remove the access in your Microsoft account or ask us to do so.

How long we keep data

• Demo: misuse values for 90 days. What you write and the conversation are not stored by us.
• Waiting list: until you ask us to delete it.
• Account: for as long as you are a customer.
• When the subscription ends: logins and keys are deleted immediately. Other data is deleted no later than 30 days after it ends.
• Accounting: accounting information is kept for 5 years under the Danish Bookkeeping Act.
• Calls and messages: a business's conversations are stored as text for as long as the business is a customer, and the business can ask us to delete them. At the voice provider, calls, including any audio, are deleted after 30 days.

Your rights

You have the right to access your information, to have it rectified or erased, to restrict processing, to object, and to receive your information (data portability). If the processing is based on your consent, you can always withdraw it. This does not affect processing that took place before. Write to kontakt@callster.dk. We respond within 30 days.

Deletion of your data

You can always ask us to delete your data, including data from Messenger, Instagram and Google. How to do it, what is deleted and how long it takes are described at callster.dk/slet-data.

Privacy contact

Callster I/S, CVR no. 46808266, Jægerstræde 8, 2690 Karlslunde. Email: kontakt@callster.dk.

You can lodge a complaint with the Danish Data Protection Agency (Datatilsynet), datatilsynet.dk.