The Most User-friendly
Secure Communication

Unfortunately, we need to inform you that Kullo will be closing on October 16th, 2020. For more information, please see this blog post.

Secure communication
now possible for everyone

  • Worldwide
    Communicate with your colleagues and friends across national borders and access your personal inbox on your mobile devices, no matter where you are.
  • Secure
    We integrate industry leading end-​to-​end encryption right into the product. Literally no one apart from you and the recipient can read your documents – including us.
  • User-friendly
    By hiding all the technical details and removing all distractions, you can simply focus on your content with your contacts.

»Kullo keeps what others promise – with good usability«

t3n Magazin

»Kullo offers free end-to-end encryption based on established algorithms. Besides private users, small companies in particular that regularly work with confidential information will be happy about the messenger.«

CHIP Software-Redaktion

The future
now on your screen

  • Encryption by default
    Within the Kullo environment, commu­nication is always secure. Messages are only decrypted locally on the user’s device.
  • Cross-platform
    Works on Windows, OS X and Linux as well as mobile devices running iOS or Android.
  • Group conversations
    Start a group conversation and send messages to multiple recipients at once.
  • Attachments
    Use drag and drop to attach files of any format totalling up to 100 MB per message.
  • Synchronization
    Automatically synchronized messages on all your devices, without any intermediate unencrypted cloud storage.
  • Notifications
    Turn on email notifications to see when something happens in your secure inbox – without message content of course.

Getting started with Kullo
will always be free

  • Free

    0 €
    Basic subscription
    • 1 GB storage
    • Default domain:
  • Friend

    9 €
    per month per user1
    • 10 GB storage
    • Default domain:
    • Supporting the purpose
  • Professional

    15 €
    per month per user2
    • 15 GB storage
    • Custom domain possible (5 €/mon. per domain)
    • Premium support
    • Uptime guarantee
  • VAT
    1 B2C offer: price includes VAT 2 B2B offer: price plus VAT
  • Availability
    Right now, available in Germany only (contact us if you want to buy from another nation)
  • Cancellation
    Cancelable at any time with 24 hours notice (prepayment will be refunded pro rata)
  • Payment
    Paid by invoice, annually in advance

It's that simple

3 steps

The work that Kullo does
for you behind the scenes

Crypto Diagram

Six steps how encrypted Kullo documents are sent:

  1. Download the private Key Store to the user’s client device
  2. Open Key Store with your personal secret to get your private signing key
  3. Sign document with private key
  4. Download receiver's public key
  5. Encrypt using receiver's public key
  6. Drop signed and encrypted document into receiver’s inbox

And all of this is done completely automatically.

Creative. Innovative. Game-Changing.
A strong team coverering all competencies

Christian Schachmann


Simon Warta

Co-Founder / CEO

Daniel Seither

Co-Founder / CTO

asked questions

What does Kullo mean?
Simon brought the word "Kullo" with him as a souvenir from The Gambia (West Africa). It means "secret" in the Mandinka language and therefore perfectly describes our vision. It also sounds amazing in Morse code:
Who are you?
We're a young tech team with backgrounds in computer science, mathematics and physics. We are passionate about data security and privacy. Still, we're not too nerdy to understand that PGP is by far not user-friendly enough for mass adoption.
What is the Kullo protocol?
The Open Kullo Protocol is a new, open communication protocol developed by us which includes end-to-end encryption as one of its main pillars. We believe that by making this protocol openly available we can enable companies to send confidential documents like invoices securely to their customers and third party developers to build great Kullo client software. We are the first provider of an inbox service based on the Kullo protocol.
How secure is Kullo? Does Kullo use new cryptographic algorithms or technologies?
Kullo relies on established cryptographic algorithms that have been checked by security experts around the world. Therefore we can guarantee the best security available. On top of these algorithms we build an integrated transport and key management system that allows users without any technical background knowledge to use Kullo.
What information is required to use Kullo?
As long as you use the Free account, we ask you for your Kullo address of choice and a personal password. This password remains your secret and will never be sent to our servers in plain text. For paid accounts we need your full name and payment information.
What information is stored on the Kullo servers?
In order to be able to do our job as a Kullo inbox provider, we need access to a few unencrypted pieces of data: your Kullo address, your public keys and some basic meta data on your account, such as the date and time of your registration and the invitation/reservation code used (if any). All of your Kullo messages, private keys et cetera are already encrypted when they reach our servers and cannot be decrypted without knowledge of your or the recipient's private keys. We can only see the number and sizes of messages and their attachments, the date and time when they where received on our server, and date and time of the latest modification (but not the content) of the message's meta data (such as read/done state). For deleted messages, we only retain the information that there has been a message with a given ID and the date and time of the deletion. Additionally, we get some information for every access to the Kullo server, because this is how the HTTP protocol works. This includes, amongst other data, the public IP address of the device accessing the server. However, we don't store IP addresses at all and carefully remove all other potentially identifying information before we store these records to gain basic insights into usage of our server.
Where will my data be stored?
We store your data on servers in Germany, where we have strong data protection laws.
When can I use Kullo?
The free version of Kullo for Desktop is available since February 2015. Premium features and mobile versions will follow in the course of the year. Make sure to sign up on our mailing list if you don't want to miss the next major milestone.
What does it cost?
There will always be a fully usable free Kullo account with a generous storage allocation. For a monthly fee (approximately the price of a lunch) we will offer a premium account that includes even more storage and professional features like custom domains.

Join our journey.

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