Download PDF Download Word Deutsch

Freelance · Software Engineering

Jens Laufer

Forward Deployed Engineer — autonomous AI agents and the harness that makes them reliable

Harness & Agentic Engineering · Forward Deployed · Python · LLM agents / MCP · RAG · Enterprise integration · Java / Spring Boot · Vue 3 · Docker

~16 years of full-stack engineering (freelance since 2009), a second track in data science and machine learning — and since late 2025 harness and agentic engineering: the scaffolding around an LLM that turns a language model into a system you can leave running. Complex projects delivered agile and test-driven, always close to the client.

Available
from 15 September 2026
Works
worldwide
Remote share
95 %5 % on-site
Day rate
€2,000/dayexcl. VAT
Based in
Karlstein am MainGermany

Focus

  • ~16 years of full-stack engineering (since 2009), freelance throughout.
  • Java/Spring Boot microservices with Vue.js and React front-ends — end-to-end with Docker, Kubernetes and GitLab CI.
  • Strictly test-driven (TDD, JUnit, Mockito, Playwright/Selenium).
  • Second track in data science and machine learning — Udacity ML Engineer & Data Analyst, Kaggle, writer at Towards Data Science.
  • Broad industry exposure: banking/finance, insurance, automotive, telecommunications, travel, industry, retail, marketing and startups.

Roles

Full-stack engineering Solution design Backend engineering DevOps Build & configuration management Data analysis Prototyping Machine learning Jenkins plugin development Maven plugin development

Skills

Languages

JavaJavaScriptTypeScriptPythonRGroovy

Microservices / Backend

Spring BootSpringSpring DataSpring IntegrationSpring SecurityOAuth2MicroservicesFeignSleuthZipkinPython EvePython FlaskJava EEEJB

Frontend

Vue.jsReactAngularJSGWTQuasarHTMLCSSBootstrap

Persistence / Databases

MySQLMongoDBPostgreSQLOracleNeo4jJPAHibernate

DevOps / Cloud

DockerKubernetesRancherGitLab CIJenkinsMavenGruntnpmArtifactoryAWS (EC2, S3, SageMaker, VPC)Microsoft AzureDigitalOcean

Security / IAM

KeycloakSpring SecurityOAuth2

Testing

JUnitTDDMockitoSeleniumDBUnitPlaywright

API / Integration

RESTSwaggerOpenAPISOAPWebservicesCXFXFireKafkaServiceMix

Machine Learning

scikit-learnKerasDeepLearning4JCNNTransfer LearningSupervised/Unsupervisedk-meansPCAt-SNEReinforcement LearningOpenAI GymTopic Modeling

Data Science

pandasnumpydplyrJupyterRMarkdownggplotseabornVega-LiteA/B TestingWebscraping

Tooling / Other

GitGitLabSubversionJiraConfluenceKibanaANTLRJavaCCZXing (QR)PayPal APIRDF/XML/JSONSAP (BAPI)PhonegapJBossTomcat

Project history

since 12/2025
ongoing

Autonomous AI agent systems — Harness & Agentic Engineering

Solytics GmbH · Remote — AI / SaaS

Harness engineering · Agent engineering · AI system architecture · Full-stack engineering · DevOps

Building and running autonomous LLM agent systems as a harness engineer — the engineering around the model, not the model itself. The harness is the product: the agent loop and its stop conditions, tool use over MCP, layered memory (durable facts, running context, session state), approval gates for anything irreversible, quality gates that must pass before an agent may ship, observability over every run, budget and rate-limit control with model routing and fallback, plus recovery when a run is killed mid-flight. A local multi-model proxy keeps the whole thing independent of any single provider. Two systems in production: a self-directing AI business partner that plans, writes code, tests and deploys around the clock, and Fabrik (fabrikhq.com), a multi-agent platform for autonomous software delivery with parallel worker agents. Event-driven orchestration over Telegram, GitHub and systemd; several AI-built SaaS products shipped end to end.

Claude / Anthropic APILLM-AgentenAgent HarnessMulti-Agent-OrchestrationTool Use / MCPRAGPrompt EngineeringPythonFastAPIVue 3GoDockersystemdGitHub ActionsDigitalOceanSQLiteTDDTypeScript
07/2024–06/2025
12 months

Digital property profile for owners

verkaufe.immobilien · Remote — Internet

Full-stack engineering · Solution design · DevOps

Full-stack development of a digital property profile that owners create and maintain themselves: Vue.js front-end, Python back-end (Eve) with a REST API and MongoDB. Day-to-day GitLab work (version control, merge-request and review workflow); built and maintained the GitLab CI pipelines for automated build and deployment. Worked to DevOps principles, owning build and operation of the services in Docker. Test-driven development, automated end-to-end tests with Playwright.

PythonPython EveMongoDBTDDVue.jsDockerGitLabGitLab CIRESTPlaywright
07/2022–04/2024
22 months

Front- and back-end, heating cost billing

Brunata · Remote — Industry

Full-stack engineering · Solution design · DevOps

Production server-side services and APIs in Java and Spring Boot: a microservice that parses and generates heating-cost files in the Haweiko-Arge industry format. Designed and built in a microservices architecture with REST interfaces (OpenAPI, Swagger), secured with Spring Security and Keycloak, persisted in MongoDB. Day-to-day GitLab work (version control, merge-request and review workflow); built and maintained the GitLab CI pipelines for automated build and deployment. Worked to DevOps principles, owning build and operation of the services in Docker. Test-driven development (JUnit, Mockito), automated end-to-end tests with Playwright. Front-end development.

JavaSpring BootMongoDBJUnitTDDReactDockerGitLabGitLab CISpring SecurityKeycloakMockitoOpenAPISwaggerRESTMicroservicesPlaywright
01/2022–06/2022
6 months

Payment back-end migration Java EE → Spring Boot

Condor · Remote — Marketing

Backend engineering

Migrated an EJB-based Java EE payment back-end to Spring Boot and shipped it as a Docker container.

JavaJava EEJPASpring BootMySQLDockerMockitoJUnitTDD
04/2021–11/2021
8 months

Software and data analysis in marketing

DigitalMarketer.com · Remote — Marketing

Full-stack engineering · Prototyping · Solution design · Data analysis

Server-side services in Java and Spring Boot: web-scraping microservices plus microsites (Vue.js, Quasar) with a Spring Boot back-end for calculators, surveys and questionnaire funnels; data analysis in R. Designed and built in a microservices architecture with REST interfaces (OpenAPI, Feign), persisted in PostgreSQL and MongoDB. Day-to-day GitLab work (version control, merge-request and review workflow); built and maintained the GitLab CI pipelines. Worked to DevOps principles, owning build and operation of the services in Docker and Kubernetes. Test-driven development (JUnit, Mockito).

ScrumSpring BootDockerKubernetesMicroservicesRESTRPythonJavaOpenAPIFeignJUnitTDDMockitoVue.jsQuasarMongoDBdplyrGitLab CIGitLabPostgreSQLPython EvePython FlaskDigitalOceanWebscrapingA/B TestingTopic Modeling
01/2021–03/2021
3 months

Marketing campaign tooling

DigitalMarketer.com · Remote — Marketing

Full-stack engineering · Solution design

Tools that generate marketing campaigns and publish them to Google Ads and Twitter Ads: Java/Spring Boot microservices with REST interfaces (OpenAPI, Feign), Vue.js/Quasar front-end, storage in AWS S3. Designed and built in a microservices architecture. Day-to-day GitLab work (version control, merge-request and review workflow); built and maintained the GitLab CI pipelines. Worked to DevOps principles, owning build and operation of the services in Docker and Kubernetes. Test-driven development (JUnit, Mockito).

ScrumSpring BootDockerKubernetesMicroservicesRESTJavaOpenAPIFeignJUnitTDDMockitoVue.jsQuasarAWS S3GitLab CIGitLab
12/2019–12/2020
13 months

Web-based configuration of telecommunications devices

Deutsche Telekom · Darmstadt/Remote — Telecommunications

DevOps · Build & configuration management · Full-stack engineering

Took over an existing prototype for configuring telecommunications devices over a web interface, developed it further and moved it into production. Production server-side services and APIs in Java and Spring Boot in a microservices architecture (REST, Feign, Spring Data/JPA), Vue.js front-end, secured with Keycloak, persisted in MySQL and MongoDB. Worked to DevOps principles, owning build, operation and monitoring of the services: Docker and Kubernetes (Rancher), logging and tracing via Kibana, Sleuth and Zipkin. Day-to-day GitLab work (version control, merge-request and review workflow); built and maintained the GitLab CI pipelines for automated build and deployment. Test-driven development (JUnit, Mockito).

JavaSpring BootDockerKubernetesMicroservicesRESTSpring DataJPAJUnitTDDMockitoVue.jsMySQLMongoDBHTMLCSSGitLabGitLab CIRancherKibanaFeignKeycloakSleuthZipkin
07/2019–12/2019
6 months

Training a stock-trading agent

JiGaoTrading · Remote — Finance

Machine learning · Data analysis

An agent that trades autonomously on Chinese stock exchanges (reinforcement learning).

Reinforcement LearningPythonRDockerAWS S3OpenAI GymGitLabseabornAWS SageMakerMongoDB
04/2019–08/2019
5 months

Data analysis and modelling at a consumer cooperative

Co-operative Group (Coop) · Manchester — Finance, Retail

Machine learning · Data analysis

Exploratory data analysis, data cleaning, aggregation; unsupervised learning (clustering, feature reduction).

RPythonJupyterRMarkdownggplotscikit-learnpandasnumpydplyrk-meansPCAt-SNEDockerGit
11/2018–03/2019
5 months

Image homogeneity of product niches from product photos

Sellics · Remote — E-commerce

Machine learning · Data analysis

A model that quantifies the image homogeneity of Amazon product niches to spot under-served niches early. Trained a ResNet50 CNN with transfer learning (Keras) and deployed it through a build pipeline as a Java microservice with DeepLearning4J into the existing landscape; prepared a Kafka data pipeline for continuous retraining.

PythonKerasResNet50Transfer LearningCNNDeepLearning4JJavaKafkaMicroservicesDocker
06/2018–10/2018
5 months

Aesthetic classification of Airbnb photos

AirDNA · Remote — Travel

Machine learning · Data analysis

A microservice that scores the quality of Airbnb photos: a Python scraper built an image database (~15k images), labelling via Amazon Mechanical Turk, exploratory data analysis in R; trained a CNN with transfer learning (Keras, ResNet50) on an AWS GPU instance and deployed it as a Spring Boot microservice with DeepLearning4J.

JavaPythonKerasResNet50CNNTransfer LearningDeepLearning4JSpring BootRAWSGPUJenkinsAmazon Mechanical TurkWebscrapingMicroservices
08/2017–03/2019
20 months

Connected Van — driver's logbook

Volkswagen · Remote — Automotive

Backend engineering

Microservices for vehicle geolocation and a fuel logbook.

Spring BootDockerKubernetesMicroservicesRESTJavaMavenSwaggerOpenAPIFeignSleuthZipkinMySQLMongoDBJiraConfluenceJUnitTDDMockitoMicrosoft AzureKibanaSpringGitKafka
04/2017–07/2017
4 months

Invoice management platform (SME) — ML

Deutsche Verrechnungstelle / DVAG · Frankfurt a. Main — Insurance, Finance, Startup

Machine learning · Data analysis

Data analysis; prototype for predicting incoming payments (ML).

PythonRggplotscikit-learnpandasnumpyseabornRMarkdownJupyterGit
07/2015–07/2017
25 months

Invoice management platform (SME)

Deutsche Verrechnungstelle / DVAG · Frankfurt a. Main — Insurance, Finance, Startup

Full-stack engineering

Platform covering the full invoice life cycle (creation, payment, dunning, debt collection); a range of Spring Boot microservices.

Spring BootDockerKubernetesMicroservicesRESTJavaMavenSpring SecurityOAuth2Spring IntegrationMongoDBJiraConfluenceJUnitTDDMockitoSeleniumAngularJSGruntnpmSpringGit
02/2015–06/2015
5 months

Invoice management platform (SME) — debt-collection integration

Deutsche Verrechnungstelle / DVAG · Frankfurt a. Main — Insurance, Finance, Startup

Full-stack engineering

Microservice integrating a debt-collection provider

Spring BootDockerKubernetesMicroservicesRESTJavaMavenSpring SecurityOAuth2Spring IntegrationMongoDBJiraConfluenceJUnitTDDMockitoSeleniumAngularJSGruntnpmSpringGit
01/2015–02/2015
2 months

Invoice management platform (SME) — OAuth2 service

Deutsche Verrechnungstelle / DVAG · Frankfurt a. Main — Insurance, Finance, Startup

Full-stack engineering

OAuth2 microservice with an administration front-end.

Spring BootDockerMicroservicesRESTJavaMavenSpring SecurityOAuth2MongoDBAngularJSGit
09/2014–12/2014
4 months

Invoice management platform (SME) — prototype

Deutsche Verrechnungstelle / DVAG · Frankfurt a. Main — Insurance, Finance, Startup

Full-stack engineering · Solution design · Prototyping · Build & configuration management

Evaluation of microservices and SPA approaches, prototype for an invoice management platform.

JavaJavaScriptHTMLCSSSpringBootstrapAngularJSGruntnpmSpring BootDockerKubernetesMicroservicesRESTMavenSpring SecurityMongoDBJiraConfluenceGit
01/2014–08/2014
8 months

Vehicle configurator prototype

Audi · Remote — Automotive

Full-stack engineering · Solution design · Prototyping · Build & configuration management

SPA on AngularJS (front-end) with a Spring back-end and a RESTful API; comparison of persistence approaches (MySQL, MongoDB, Neo4j).

JavaJavaScriptHTMLCSSBootstrapSpringSpring SecuritySpring DataMongoDBNeo4jMySQLMavenTomcatJUnitTDDMockitoSeleniumJiraGit
06/2012–12/2013
19 months

Business services for a booking and reservation system

Deutsches Reisebüro (DER) · Frankfurt a. Main — Travel

Backend engineering

Implementation of business services as part of the re-build of a booking and reservation system.

JavaJUnitTDDMockitoSpringSOAPWebservicesJiraMaven
05/2011–04/2012
12 months

QR-code based payment solution

Paycoo Ltd. · London — Finance, Startup

Full-stack engineering · Solution design · Build & configuration management

Money transfer between accounts by scanning a QR code; hybrid app (GWT) embedded in native mobile apps for broad platform coverage.

JavaJUnitTDDMockitoGWTPhonegapSpringSpring SecurityJPARESTZXingPayPal APIMavenAWS EC2AWS VPCJenkinsArtifactory
10/2010–02/2011
5 months

Entry testing (EntryCheck) of application server environments

Deutsche Telekom · Darmstadt — Telecommunications

Jenkins plugin development · Maven plugin development

Test environment for the technical entry testing of runtime environments (build and deployment) for a large Java EE enterprise application.

JavaMavenJenkinsGroovySubversion (SVN)
04/2010–09/2010
6 months

Web services on an ESB (mediation and rating)

1&1 · Montabaur — Telecommunications

Backend engineering

Software design, web services, maintenance of the rating engine; web services that hand invoices over to SAP.

JavaSpringSpring SecurityJPAHibernateMavenJUnitTDDMockitoDBUnitServiceMixWebservicesCXFXFireSAP-AnbindungSAP BAPIJBossOracleSubversion (SVN)
05/2009–03/2010
11 months

Master data migration at a major bank

Commerzbank · Frankfurt a. Main — Banking, Finance

Backend engineering

Workflows for persisting master data, a canonical XML model, RDF description for machine processing.

JavaJava EEIBM MDM (WCC)EJBJPARDFXMLOracleSubversion (SVN)

Contact & Credentials

Contact & profiles

Education

11/1997
Dipl.-Ing. (Univ.) Electrical Engineering (MSc equivalent)
University of Erlangen-Nuremberg
05/1989
Abitur (university entrance qualification)
Gymnasium am Romäusring, Villingen-Schwenningen

Certificates

12/2018
Machine Learning Engineer Nanodegree
Udacity
Verify →
08/2017
Data Analyst Nanodegree
Udacity
Verify →