Senior Software Engineer

at Booking.com

📍 Amsterdam, Netherlands

EUR 55-120 per hour

SENIOR

✅ Hybrid ✅ On-site

✅ Contract / Freelance

Tech Stack
Tag name is followed by "@" symbol and proficiency level value. About proficiency levels:

1-2 — basic awareness. Minimal hands-on experience, and a rudimentary understanding of the technology's purpose;

3-6 — daily use. Comfortable and regular usage, capable of handling common tasks and challenges related to the technology;

7-9 — you are an expert, you can teach others, you know all the pitfalls and tricks;

10 — exceptional knowledge, comprehensive understanding, and adeptness in all aspects of the technology, including advanced problem-solving. Think twice before claiming or demanding such level.

API @ 6 Communication @ 7 Distributed Systems @ 4 Java @ 7 Kafka @ 4 Python @ 7

Details

We are seeking a senior software engineer consultant to build production-ready URN libraries in Java and Python and contribute to the resolver service that maps identifiers across a large-scale data platform.

Different systems often represent the same entity using inconsistent identifiers. This creates ambiguity, duplicated mapping logic, brittle integrations, and unnecessary maintenance.

You will help create a shared, machine-readable identifier standard and developer library that enables teams to generate, parse, validate, and safely evolve identifiers across services.

Responsibilities

Design and implement equivalent Java and Python library APIs.
Support canonical, extension, and nested/composite identifiers.
Implement robust parsing, validation, and actionable error handling.
Create a maintainable catalog-driven model for identifier types and validation rules.
Define compatibility, versioning, and release practices.
Build comprehensive automated tests and CI quality checks.
Publish clear documentation, examples, and adoption guidance.
Collaborate with architects and domain teams to onboard initial identifier types.
Contribute to resolver-service APIs and logic for mapping between canonical and extension identifiers when external lookup is required.
Work independently from design through MVP delivery and stabilization.

Requirements

Strong production experience with both Java and Python.
Experience building reusable libraries, SDKs, or platform components.
Excellent API design, parsing, validation, and testing skills.
Understanding of distributed systems and service-oriented architecture.
Experience with schemas, catalogs, metadata, resource naming, or identity systems.
Strong communication skills and comfort working across teams.

Nice to Have

Kafka or event-streaming experience.
OpenLineage, data lineage, metadata, knowledge graph, or data catalog experience.
Experience publishing and maintaining multi-language packages.