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Cosmo, the open-source GraphQL Federation project, is seeking a Senior/Staff Golang engineer to join our fully remote team. You will develop, refactor and maintain the GraphQL Router backend written in Go, and collaborate with product and success teams to shape its evolution.
We value performance, low garbage collection, security and deep technical ownership, with opportunities to travel occasionally and grow with us.
the company is a fast-growing startup, our goal is to bring everybody together to build digital products end-to-end. From interface design to API implementation, we provide the platform to go from sketch to product in a category-defining collaborative experience. Our North Star is to take the friction out of bringing digital ideas to life, making room for your ideas and productivity.
Developers from some of the biggest companies in the world are using the company to design and streamline their API environments. We raised our Series A ($7.5 million USD) in March 2025, being backed by eBay, Karma Ventures, and Aspenwood Ventures.
The culture we are creating together is extremely important to us. Read here how we are Building the Company We Always Wanted to Work In.
We invite everyone that wants to join us to understand our Core Beliefs and if you want to make an impact, have your voice heard, and work in a no-BS organization where you can get stuff done,
We're building the company Cosmo, the open-source GraphQL Federation solution. Probably the most important component of Cosmo is the Cosmo Router, which - simply put - connects all API endpoints and handles the GraphQL requests and responses whilst applying the Federation protocol (among other magical things, like normalization, execution planning etc.). Fully written in Go, it's the fastest GraphQL Router available and a quite potent (and complex) piece of cutting-edge open-source software. How about joining our team to make it even better and strap the rocket boosters onto GraphQL Federation?
You will be in charge of Develop, refactor and maintain GraphQL Go Tools' (Router) open-source code base in Golang (low GC code)
The "Engine" is essentially a Golang application which translates GraphQL requests into any other protocol, like OpenAPI, SOAP, gRPC, GraphQL, Apollo Federation, etc. You could consider the Engine as a "GraphQL Compiler" or Transpiler. The Engine is responsible for parsing, normalization, execution planning, execution runtime, etc... If you are interested in working with ASTs, AST transformations, etc... you will love this kind of work. We have performance requirements, so you should be proficient in writing performant and low GC code in Golang.
Some of your tasks will take more than a few weeks to complete, Ideally, you're someone who likes to go deep on one topic instead of going wide and shallow on many different topics.
Here's a list of things you might be working on:
What you bring to the team Senior/Staff level of proven Golang development experience in a leading / ownership role (must have)
Customers love our product because it works flawlessly, securely and fast - and because it looks darn pretty, too!
Work from wherever you thrive—we’re fully remote and globally distributed. If you're in Miami, come work with us in person! We also provide co-working space options worldwide if needed.
We respect your time and interest in the company. This is why we're aiming to make the process as fast as possible. Here's what you can expect:
Our process also includes reference and background checks. We aim to respond or provide feedback in 2 or 3 days between each stage of the process. We're usually hiring through Deel as our Employer of Record, except for Germany or Florida where we're hiring directly.
the company is an equal opportunity workplace; we welcome people from all backgrounds.
You can find out more about our ways of working together here:
the company Public Handbook and Resources
We’re looking forward to your application so we can grow together!
Compensation: €90K – €130K