Senior Backend Developer (Ruby) – (m/f/d)
in Berlin

This is a freelance opportunity with the possibility of turning into a permanent role.

Job summary

We are looking for a Senior Backend Developer to join our new cutting-edge venture: AI Business travel assistant Swifty (more about Swifty below).

We are seeking a highly skilled and experienced senior backend developer to join our exciting startup and take the lead in building our LLM-based startup from the MVP. 

As the first full-time developer on the team, you will have the opportunity to make a significant impact and shape the future of our company. We are backed by Lufthansa Innovation Hub, providing a strong foundation for growth and success. 

This position offers the possibility to join as a permanent employee after freelancing, providing long-term stability and the chance to grow with the highly ambitious startup. 


The Stack

  • Ruby on Rails backend with Sorbet for type checking
  • Python and Langchain for LLM flows
  • Postgres database
  • Terraform for managing AWS infrastructure
  • Bonus: Amazon Web Services (RDS, ECS, Lambda, Cloudwatch)
  • Bonus: TypeScript, React


How we work

  • Hybrid setup, or remote with some travel to HQ in Berlin
  • For complex features, write a design doc before coding
  • All code goes through code review, reviews are split out evenly across the team
  • We use Tuple for pair programming
  • We use Slack for async communication



  • A keen interest or real-world experience in building LLM applications, ideally using Langchain.
  • Track record of shipping products across the entire stack. You’re not afraid to pick up new languages or tools as required. 
  • You understand when to ship quickly to validate a concept vs moving deliberately to avoid trapdoor decisions.
  • Experience integrating complex third-party APIs
  • Able to handle ambiguity, and can push projects forward even when there is not a clear best path
  • You can manage yourself but you also work well with others
  • Fluent English and good communication skills


About Swifty & Lufthansa Innovation Hub

Swifty is the first autonomous AI tool in the travel industry that has already generated first revenue and was recognized by multiple media outlets and startup awards. Swifty was incubated at the Lufthansa Innovation Hub, and is transitioning into a founder-led independent company. We transform the time-consuming and fragmented business travel booking process into a fast and efficient experience. The AI-based assistant autonomously manages essential steps of business travel, encompassing planning, booking, payment, and invoicing – all within the chat interface. 

  • Swifty has engaged >1500 users and was recognized by multiple German and International media outlets, including Welt, Tagesspiegel, Handelsblatt, Frankfurter Allgemeine Zeitung, Phocus Wire
  • At Lufthansa Innovation Hub, we’re pioneering the future of travel for the Lufthansa Group, the industry, but most importantly for everyone who travels
  • Lufthansa Innovation Hub identifies market shifts and translates them into new business opportunities in the travel sector by building a valuable portfolio of travel companies and products


At LIH, we are super committed to fostering an environment that promotes diversity and inclusivity. We do not discriminate in employment on the basis of factors irrelevant to merit, qualifications or business need such as age, race, color, sex, sexual orientation, gender identity, marital status, disability, medical status, or any other status covered by the relevant law in the areas where we operate.

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Please send your application to

[email protected]