Software Engineer (APIs and Integrations)

We are seeking an experienced Software Engineer to join our APIs & Integrations team in Sofia (full – time, hybrid).

You will design, build, and evolve our .NET/AWS data delivery platform across three modes: public REST APIs (on – demand access), feeds (continuous, delta – only updates via SFTP/FTP, S3 with SQS – orchestrated workflows), and dumps (one – time, large exports). You’ll also own SDKs – both auto – generated from OpenAPI/Swagger and tailored, user – friendly libraries for non – developer audiences (e.g., quants).

Our stack relies on Elasticsearch and Aurora MySQL, supports JSON and XML output formats, and does not use streaming.

You’ll collaborate with Product, Data, Support and CloudOps to ship reliable, secure, well – documented services at scale.

The ideal candidate should have:

A Bachelor’s degree in Computer Science or Information Technology (or equivalent experience) and at least five years of production software development experience are required.

Strong proficiency in C#/.NET (ASP.NET Core) and a track record of shipping public REST APIs with JSON and XML, including sound versioning, pagination, idempotency, and rate limiting, are essential.

Hands‑on experience with AWS – especially API Gateway, S3, SQS, and IAM – and the ability to design secure, reliable, and cost‑aware services are expected.

Demonstrated delivery of data via REST, delta feeds over SFTP/FTP and S3 with SQS orchestration, and bulk dumps – implemented as resilient, resumable, and monitored flows – is required.

Proficiency with MySQL (Aurora) and Elasticsearch.

Proficiency with OpenAPI/Swagger design and client SDK generation, together with a security‑first mindset, disciplined testing (unit, integration, contract), practical observability (logging, metrics, tracing), and effective collaboration in a hybrid environment, is essential.

Strong plus is:

Exposure to Snowflake integrations – such as data shares, roles, and views – with readiness to learn more on the job is advantageous.

Experience building user‑centric SDKs and tooling for Python or R audiences and publishing packages to common registries is a plus.

Familiarity with data‑delivery quality controls (manifests, checksums) and the ability to partner with CloudOps on Docker, Terraform, and CI/CD are beneficial.

Background knowledge of financial data or capital markets is welcome.

Responsibilities:

Deliver solutions across four main channels – public REST APIs, delta feeds, bulk dumps, and Snowflake integrations – without streaming.

Design, stablish and enforce API design standards – captured in highquality, examplerich OpenAPI specifications – to ensure public REST APIs are coherent and easy to consume, with consistent resource models, intuitive naming, predictable pagination and error contracts, stable versioning, and reliable autogenerated client SDKs.

Build .NET based services that follow clean OpenAPI contracts, provide robust JSON and XML support, and apply disciplined versioning, pagination, filtering, idempotency, and throttling.

Orchestrate delta feeds and large exports over SFTP/FTP and S3 by using SQS for scheduling, retries, and back‑pressure, and design pipelines to be resumable and auditable.

Build versatile processes to publish datasets to Snowflake, and document usage patterns while validating cost and performance.

Generate client libraries from OpenAPI and develop targeted, user‑friendly SDKs and examples for quantitative users.

Query MySQL and Elasticsearch database targeting performance and efficiency.

Embed unit, integration, and contract tests into continuous integration, instrument services with logging, metrics, and tracing, and set and track meaningful SLOs.

Maintain clear API references, integration guides, and how‑tos, and partner cross‑functionally with Product, Data, and CloudOps to scope, deliver, and iterate.

What we offer:

Interesting and fulfilling projects

Great working environment in an international company

Open and friendly working atmosphere

Work-life balance

Hybrid working model of 2 days in the office and 3 days from home

4 weeks a year you can work from any location that you choose.