Senior Java Developer - Startup - Fintech/Cryptography/Digital Identity


At Citizen , we’re building a digital legitimacy platform for the secure exchange of identity.

Our platform combines world class cryptography with simple mobile experience to offer a simple way to secure your digital identity. Our legitimacy product makes establishing real world checks accessible to both businesses and individuals.


Our mobile platforms perform local and remote cryptography to secure identity using traditional and biometric methods. We are obsessive about the security of devices and our users, so we test heavily internally, and using external grey hat services. Our mission is to protect consumer data like no other.

Our API platform scales to 1000’s requests/sec and needs to offer near RTP of cryptographic data exchanges to our customers and consumers. Equally, we are consumers of multiple external 3rd party APIs, for data that needs to be matched and aggregated in near real time.


Having recently raised a funding round, we are now working with leading banks and insurers in the financial sector, along with e-commerce companies who need cyber security for their consumer data. Our team comes from leading businesses in the UK e-commerce and payments sector and are well positioned to capitalise on this opportunity.


We are looking for senior developers, who are able to work in a rapidly changing environment, but are aware of the need for secure, robust code shipping to production. Our working environment is flexible and our approaches are goal oriented.

We’re open to new technologies and this role offers early hires the once in a lifetime chance to shape something world changing.


Required Exposure:


  • Java - Spring Boot/Data/Security/MVC using Java 8
  • NoSQL databases - MongoDB/Cassandra
  • TDD/BDD mindset - is driven by good test coverage
  • Mobile - Android/iOS is a plus

Infrastructure & Scale

  • Familiar with AWS using Docker or other container deployments
  • Understands micro-service architectures and how to build atomic services
  • Can work with external performance measurement services to adapt their code to scale (eg New Relic, Cloudsense)


  • Aware of the basic tenets eg SQL injection, DDOS, XSS, CSRF


It would be advantageous for the candidate to have exposure to one or more of the following:


  • Mobile development using React Native
  • Messaging platforms - eg Kafka/Kinesis/Storm


  • Use of encryption keys to secure data - aware of crypto strength v overhead
  • Exposure to Java Security, Legion of the Bouncy Castle or other OS libraries
  • Use of hashing and signing to protect publicly exposed data
  • Knowledge of Blockchain related technologies and crypto-currency


  • Familiar with testing APIs & infrastructure for vulnerabilities
  • Prior payments or secure processing experience - understands tokenisation

Salary is negotiable, and equity (stock options) are available for the right candidate.

Email for more information, including your CV and GitHub ID.