Expert Systems AG

Technology, Information and Internet

51-200

Germany

At Proven Expert, we believe that trust is the most important currency in business. Since 2011, we have been building a platform that now enables more than 1.1 million service providers, freelancers, and companies to make authentic customer feedback visible – and become more successful. Our tools help to use reviews in a targeted way – for better visibility in SEO and social media as well as for a strong online reputation.

Our headquarters are in Berlin, with another office in Madrid. Our team is just as international as our customers. We work together across borders, both digitally and on-site, always with the shared goal of making trust tangible and usable online.

What you can look forward to**:** Every idea counts with us. We are a team that values initiative.

## Tasks

**What You’ll Do**

*   Develop and maintain scalable backend services with NestJS, Node.js, TypeScript, and TypeORM.
*   Build and optimize js / React frontends that deliver great user experiences.
*   Design and maintain GraphQL (Apollo) and REST APIs used across teams and products.
*   Work with Kubernetes in production environments (OVH, AWS, or GCP).
*   Implement secure authentication and authorization flows with Keycloak.
*   Write clean, well-tested code and contribute to automated testing (unit, integration, E2E).
*   Collaborate with Product, Design, and Business teams to bring ideas to life.
*   Contribute to code reviews, best practices, and knowledge sharing within the team.

## Requirements

**Your Profile**

*   3–5 years of experience in backend or fullstack development.
*   Solid knowledge of TypeScript and js (NestJS & TypeORM experience a plus).
*   Experience working with GraphQL and/or REST APIs.
*   Strong understanding of PostgreSQL (MongoDB exposure is a plus).
*   Hands-on experience with Kubernetes and containerized environments.
*   Familiarity with CI/CD workflows and Git (Bitbucket, branching, PR reviews).
*   Comfortable with Unix shells (bash/zsh).
*   Good English skills; German is a plus.
*   A collaborative team player with a passion for learning and sharing knowledge.

**Nice to Have**

*   Experience with HubSpot, Monsum, SendGrid, Bevo, or Maxio
*   Knowledge of Kafka or RabbitMQ.
*   Extra skills in PHP/Symfony, Golang, Python, or Rust.
*   Curiosity about AI developer tools (e.g., GitHub Copilot, Anthropic Claude).

## Benefits

*   An open, international team with real opportunities for development
*   Flexible working hours
*   Modern office in Berlin with the option to work from home (hybrid work model)
*   Plenty of room for ideas and the chance to actively shape the future of our platform
*   Free choice of hardware and modern tools for efficient work

**Join Our Journey**

At Proven Expert, we believe in the power of diversity. Our team is made up of talented individuals from different backgrounds, cultures, and perspectives. We value the uniqueness of every team member and foster an inclusive work environment where innovation and creativity can thrive. With us, every voice counts. We welcome applications from people of all genders, ethnic backgrounds, religions, sexual orientations, and abilities.

Ready to shape the future of online reputation management with us?

Apply now and join our team

Employee

Professional / Experienced

<p>At Proven Expert, we believe that trust is the most important currency in business. Since 2011, we have been building a platform that now enables more than 1.1 million service providers, freelancers, and companies to make authentic customer feedback visible – and become more successful. Our tools help to use reviews in a targeted way – for better visibility in SEO and social media as well as for a strong online reputation.</p>
<p>Our headquarters are in Berlin, with another office in Madrid. Our team is just as international as our customers. We work together across borders, both digitally and on-site, always with the shared goal of making trust tangible and usable online.</p>
<p>What you can look forward to**:** Every idea counts with us. We are a team that values initiative.</p>
<h2 id="tasks">Tasks</h2>
<p><strong>What You’ll Do</strong></p>
<ul>
<li>Develop and maintain scalable backend services with NestJS, Node.js, TypeScript, and TypeORM.</li>
<li>Build and optimize js / React frontends that deliver great user experiences.</li>
<li>Design and maintain GraphQL (Apollo) and REST APIs used across teams and products.</li>
<li>Work with Kubernetes in production environments (OVH, AWS, or GCP).</li>
<li>Implement secure authentication and authorization flows with Keycloak.</li>
<li>Write clean, well-tested code and contribute to automated testing (unit, integration, E2E).</li>
<li>Collaborate with Product, Design, and Business teams to bring ideas to life.</li>
<li>Contribute to code reviews, best practices, and knowledge sharing within the team.</li>
</ul>
<h2 id="requirements">Requirements</h2>
<p><strong>Your Profile</strong></p>
<ul>
<li>3–5 years of experience in backend or fullstack development.</li>
<li>Solid knowledge of TypeScript and js (NestJS &amp; TypeORM experience a plus).</li>
<li>Experience working with GraphQL and/or REST APIs.</li>
<li>Strong understanding of PostgreSQL (MongoDB exposure is a plus).</li>
<li>Hands-on experience with Kubernetes and containerized environments.</li>
<li>Familiarity with CI/CD workflows and Git (Bitbucket, branching, PR reviews).</li>
<li>Comfortable with Unix shells (bash/zsh).</li>
<li>Good English skills; German is a plus.</li>
<li>A collaborative team player with a passion for learning and sharing knowledge.</li>
</ul>
<p><strong>Nice to Have</strong></p>
<ul>
<li>Experience with HubSpot, Monsum, SendGrid, Bevo, or Maxio</li>
<li>Knowledge of Kafka or RabbitMQ.</li>
<li>Extra skills in PHP/Symfony, Golang, Python, or Rust.</li>
<li>Curiosity about AI developer tools (e.g., GitHub Copilot, Anthropic Claude).</li>
</ul>
<h2 id="benefits">Benefits</h2>
<ul>
<li>An open, international team with real opportunities for development</li>
<li>Flexible working hours</li>
<li>Modern office in Berlin with the option to work from home (hybrid work model)</li>
<li>Plenty of room for ideas and the chance to actively shape the future of our platform</li>
<li>Free choice of hardware and modern tools for efficient work</li>
</ul>
<p><strong>Join Our Journey</strong></p>
<p>At Proven Expert, we believe in the power of diversity. Our team is made up of talented individuals from different backgrounds, cultures, and perspectives. We value the uniqueness of every team member and foster an inclusive work environment where innovation and creativity can thrive. With us, every voice counts. We welcome applications from people of all genders, ethnic backgrounds, religions, sexual orientations, and abilities.</p>
<p>Ready to shape the future of online reputation management with us?</p>
<p>Apply now and join our team</p>


Fullstack Developer (m/f/d)

Copywriter (m/w/d) / Texter (m/w/d)

Fullstack Developer (m/w/d)

Teamlead (m/w/d) Proven Expert 2.0

Working student

Werkstudent (m/w/d) im Bereich Sales & Operations (SDR)

Expert Systems AG logo

user JOIN

Google {privacyLink} and {termsLink} apply.

Benefits

Media

We don't have any open positions at the moment

No available jobs

Offices

Open positions

Values

Videos

Do you have a question?

Spontaneous Application

We’ll send a link to this job to your email.

No time? Just apply later

We are reviewing your account. Once our managers approve it, candidates will be able to apply for this job.

Changes are not visible until you publish your job.

This is a preview of your job ad.

Interested?

The job {jobTitle} was archived or the deadline has passed.

This job is no longer available

Recruiting Team

Our other open positions

We no longer accept spontaneous applications

Are you a talented professional seeking your next career adventure? At {companyName}, we appreciate proactive individuals who can bring a fresh perspective to our team.

While we may not have an immediate job opening that precisely matches your needs, your distinctive experiences and talents might be an excellent fit for us in the future.

To submit your spontaneous application, please use the application form on the right to upload your CV and cover letter. Ensure that you mention your desired position in the cover letter.

Rest assured, our dedicated recruiting team will reach out to you once they identify a role that aligns perfectly with your skills and aspirations.

How to apply

Looking for a job at {companyName}? JOIN works directly with {companyName} to bring you all their open positions. Apply now with JOIN.com.

Jobs at {companyName}. Browse all open positions and become part of our team! Open positions: {jobsCount}

Jobs at {companyName}. Browse our open jobs and join us! We currently have {jobsCount} available jobs. Step up your career and apply today!

Jobs at {companyName}. Browse all our open positions and become part of our team! We have currently {jobsCount} jobs available. Apply today to join us!

Jobs at {companyName}. Browse all open positions and become part of our team! We are currently looking for {jobsCount} additions to our company. Apply today!

Jobs at {companyName}. Browse all open positions and become part of our growing team! We are currently looking for {jobsCount} additions to our company. Apply today!

Jobs at {companyName}. Browse all our open positions and become part of our growing team! We are currently looking for {jobsCount} additions to our company. Apply today!

Browse all our open positions and become part of our team! We are looking for {jobsCount} additions to our company. Take the next step in your career and apply today!

No suitable positions available at {companyName}? Don't wait! Submit a spontaneous job application today and unlock your career possibilities tomorrow.

Our other open positionsView all open positions

Copywriter (m/w/d) / Texter (m/w/d)

Fullstack Developer (m/w/d)

Teamlead (m/w/d) Proven Expert 2.0

Werkstudent (m/w/d) im Bereich Sales & Operations (SDR)

Our other open positions
View all open positions