Giving control of the entire ticket lifecycle to event organizers

Thessaloniki, Greece

Established in 2018

Teaser of the company

ComeTogether ( provides infrastructure for event ticketing, fraud and scalping prevention along with secondary market revenue management. EOSIO blockchain ticketing engine controls the entire lifecycle of a ticket.

Developed BackTogether – COVID-19 Passports (COVID and antibody test status) when the events industry shut down during lockdowns. Functionality has been integrated into ComeTogether, adding a health component to the tickets, to enable safe restart of events.

ComeTogether has developed the following blockchain-based prototype in the scope of BlockStart:

QR code scanner native app for ComeTogether and updates on BackTogether (COVID-19 health passport app)


The scanner native app can scan QR codes representing tickets. On every scan it invalidates a ticket on the EOSIO blockchain and provides ticket status validation. The app works under low bandwidth and low battery consumption as well as in offline mode. The company managed to achieve the aforementioned goals by using MQTT protocol and MongoDB realm sync. The app is also working concurrently for many scanner devices with real time sync among those devices for events with multiple entrances.

For example, as soon as a validator scans a ticket for a specific event on one device an update occurs to all other scanner devices that are connected to this event. The app is intended to be used by the ticket validators in the entrance.

BackTogether is a COVID-19 health passport solution providing archival and status validation for COVID-19 tests (rapid/RT-PCR), antibody tests and vaccinations. The application can be interoperable with any other health passport solution (from the public or private sectors) that is required.

The health status validation is targeted for access control to sensitive or crowded places (eg., nursing homes, hospitals, airports, live events, theaters, etc.).The access control rules are customisable, with the possibility to set which tests or vaccines will be accepted, for how much time tests are considered valid etc. Therefore, making it really adaptable to ever changing government or local regulations.

Technical development during Prototype stage

During the development of ComeTogether and BackTogether, the following technical developments have taken place:

  • UI/UX updates on BackTogether app

  • Developed new BackTogether features as requested by the clients (e.g., ID scanning, refactor of our model architecture – added superadmin, added photos on QR scanning)

  • Launched BackTogether app on iOS – passports/id1538164399

  • Finalised the QR code scanner native app. More specifically:

    • Deployed an MQTT Aedes broker to an AWS EC2 instance. At the broker level of the system, the company developed all the logic around the invalidation of the tickets on the Blockchain and the distribution of the information to all the stakeholders. Using MQTT helped the team satisfy the request made by one of their partners (Eightball) who asked for the scanner to function under low bandwidth circumstances. ComeTogether tested the solution in a relevant environment with bandwidth up to 70Kb/s and all the tests passed.
    • It also implemented the MongoDB realm sync functionality which enables the app to work offline. This feature was requested also by some partners.
  • Next 12 month roadmap:

    • Integrate BackTogether into ComeTogether
    • Ticket wallet app
    • Integrate seating into ComeTogether
    • Resales
    • Organizer dashboard

Business development during Prototype stage

During the development of ComeTogether and BackTogether, the following business developments have taken place:

  • Updates on both ComeTogether and BackTogether decks

  • Talks with Attica region in Greece about BackTogether integration

  • The company progressed on closing a deal to pilot BackTogether with Iaso Thessalias

  • Published three press releases and demonstrated BackTogether solution in the Greek national TV

  • Secured a new contract with Tickets For Good

  • Attended ILMC virtual event where they met one potential German Business developer and one potential UK partner operating in merchandise as well as made other connections – e.g., in China

  • Joined SAFE hackathon where they boosted networking

  • Created ‘’ initiative to bring back live events in Greece – got the approval to pilot a live event with 400 people in Greece (May 2021)

  • Got selected by Qatar SportsTech accelerator to provide innovative solutions for major international sports events, such as the FIFA World Cup 2022

  • Hired 2 medium level software developers and almost closed a German Business developer

  • Also progressed on their fundraising – had talks with investors in Greece, as well as with the Qatar Development Bank

  • Within the next 6 months, ComeTogether is planning to hire two more medium level software developers and one business developer. Additionally, the company plans to onboard more health service providers with BackTogether app and event organizers with the ComeTogether app. In addition, they want to pilot more live events throughout Europe and Qatar. Finally, the company wants to close a Qatar Stars League team as a beta user of either BackTogether or ComeTogether and fundraise a minimum of 200.000 euros

  • Efforts to validate ComeTogether’s market/fit:

    • Reached out to more than 10 event organizers
    • Reached out to more than 4 health service providers
    • One UK ticketing company committed to a contract for both of the company’s solutions
    • Some of the biggest event organizers in Greece have shown trust for both of the company’s products (
    • They will pilot a live event of 300-400 people in Greece in May 2021

Pilot stage implementation


In BlockStart, ComeTogether implemented its “BackTogether” product in 2 SME adopters

During the Pilot stage, we released the ‘Tickets For Good’ Web App where the purchase of the blockchain tickets can take place and the Ticket Wallet App where the tickets are represented by a dynamic QR code. The apps can be used by Tickets For Good’s customers for a more advanced ticketing experience.

Main KPIs included the:

  • Finalisation of ComeTogether’s primary ticketing solution as a whitelabel
  • Technical set up of the whitelabel solution and modifications making it applicable for Tickets For Good’s requirements
  • Release of the ‘Tickets For Good’ Web and Ticket Wallet App

All KPI’s were successfully executed. As a result we have a fully functional product under Tickets For Good’s own branding.

During the Pilot stage, we made updates on the ‘Emergency Help’ Health Certificate App on both Android and iOS Platforms. The App was also used for the issuance and storage of Covid-19 test results for Emergency Help’s customers. This was a great way to get customer feedback on the product.

Main KPIs included the:

  • Update of the App
  • Issuance of Covid-19 tests in the App

Of course, constant communications and feedback with Emergency  Help were crucial in order to make things work properly and according to their needs.

SME adopters

Meet the Team

Lazaros Penteridis
Lazaros PenteridisCEO
6 years taking software products to markets.
Former software engineer for 3 years in Ortelio (cloud robotics). MEng Electrical and Computer Engineering (ECE) from AUTH.
Stavros Antoniadis
Stavros AntoniadisCo-Founder/ COO/ Head of blockchain
3 years software engineer: Blockchain engineer @ ComeTogether, CERTH. Mobile developer and test automation engineer @ Schoox. MEng ECE from AUTH.
Nikos Chatzivasileiadis
Nikos Chatzivasileiadis Co-Founder/ CTO
3 years full stack engineer @ ComeTogether, Veltio, Orfium.
MEng ECE from AUTH.
Stathis Mitskas
Stathis MitskasCo-Founder/ Head of Product
3 years full stack engineer @ ComeTogether, Accenture. Best paper on BlockSys 2018.
3 Masters: CS, Finance-Banking, Leadership.
Claudia Bacco
Claudia BaccoHead of Marketing
Formerly Global Head of Brand and Customer at Nokia and Vice President at Frequentis.
Gertruda Fon Narcco
Gertruda Fon NarccoHead of UX
Many years of UX/UI design experience. Her main focus is to help with the development of product delivery strategy, user expertise, visual design, and a proper communication strategy to the main audience
Andreas Kouloumos
Andreas Kouloumos Blockchain Developer
Software developer for 3 years(, ComeTogether). MEng Electrical and Computer Enginnering NTUA
Evangelos Antoniou
Evangelos AntoniouBusiness Development
20 years of experience in business development and sales across multiple sectors, especially in the German, Austrian and Greek markets
Antonis Papadopoulos
Antonis PapadopoulosSocial Media Manager and Graphic Designer
4 years of experience in social media marketing and content production. MSc Civil Engineer
Giannis Gkouziokas
Giannis GkouziokasFull Stack Developer
Former Software Engineer at Accenture Greece for the banking sector. Master in Electrical and Computer Engineering. MSc in Cyber Security

ComeTogether’s achievements

Media features

For more information, download the company’s portfolio and pitch deck:

We are very excited to have been given the opportunity to collaborate with experienced mentors who provided valuable advice in many aspects of our business. They helped us to pay attention to the things that had the most value for our growth. In addition, we got a lot of support/sponsorship for attending industry events, where we increased further our networking. Last but not least, the funding provided by the programme enabled more team members to come back and work full-time once again.

Efstathios Mitskas, Co-founder & Head of Product, ComeTogether

Total funding received by ComeTogether PC under BlockStart: €20,000 (€1,000 for Ideation Kick-off, €15,000 for Prototype stage and €4,000 for Pilot stage)