Charef Bahria | Senior Full Stack Engineer

01 / About

About

Full Stack Engineer with 5+ years building auth infrastructure, developer tooling, and client products across a software agency and SaaS studio.

Known for owning products end to end, from API design and TypeScript SDKs to React dashboards. Most recently the primary engineer on theauthapi.com at ThatAPICompany, where I handled the backend, frontend, infrastructure, TypeScript SDKs, and developer documentation. I also built an LLM-powered contract processing pipeline using LangChainJS and OnlyOffice Document Builder, which resulted in a merged open source contribution to the official LangChainJS repo (PR #7421).

Before that, I worked at GMD on an e-commerce platform, building GraphQL APIs, an OCR invoice pipeline in Python, and client-side tooling in a cross-functional team of six.

Based in Berlin on a Chancenkarte. Immediately available. Looking for roles where backend systems and developer tooling intersect, ideally where the work has production stakes.

Languages

02 / Experience

Where I've worked

Apr 2022 - May 2025

3 years

ThatAPICompany

Senior Full Stack Software Engineer

Led end-to-end delivery of theauthapi.com: backend, frontend (Next.js), infrastructure, TypeScript SDKs, and developer documentation
Built LLM-powered contract-processing pipeline using LangChainJS and OnlyOffice Document Builder, automating clause redlining for a client engagement
Engineered event-driven backend services in PHP and TypeScript with Sentry and CloudWatch observability for production reliability
Developed TypeScript SDKs for external clients integrating authentication APIs, reducing integration time by 40%
Designed API analytics platform on BigQuery with a real-time event ingestion pipeline
Maintained comprehensive Jest test suites (unit and E2E) ensuring reliability of the multi-tenant authentication platform

Node.jsNestJSTypeScriptPHPReactBigQueryDockerLangChainJS

May 2021 - Mar 2022

10 months

GMD

Full Stack Software Engineer

Built and maintained backend APIs using TypeScript, Apollo and GraphQL, optimizing data retrieval for a product catalogue of hundreds of SKUs
Developed OCR pipeline in Python to automate invoice data extraction, reducing manual entry time by over 70%
Built client-side image compression solution reducing upload sizes by approximately 60%, improving upload speed for on-site staff
Worked within a cross-functional team of six developers, a PM, and stakeholders to scope, review, and ship features on schedule

TypeScriptApolloGraphQLPythonMySQLPostgreSQLREST APIs

03 / Projects

Things I've shipped

TheAuthAPI

Auth SaaS platform

Solo project

Primary engineer on a production auth API with rate limiting, key management, and a React dashboard. Ships with a TypeScript SDK and a BigQuery analytics pipeline that processes usage events at scale.

Node.jsNestJSTypeScriptReactBigQueryPostgreSQLDocker

View

LLM Contract Pipeline

Automated clause redlining

Production

Built an LLM-powered contract processing pipeline using LangChainJS and OnlyOffice Document Builder, automating clause redlining for a client engagement. The work surfaced a bug in the OnlyOffice document loader, which I fixed and submitted upstream, resulting in merged PR #7421 to the official LangChainJS repo.

LangChainJSNode.jsTypeScriptOnlyOffice

LangChainJS PR #7421

Open source contribution

Merged

Contributed a fix to the official LangChain JavaScript library. The OnlyOffice document loader was not returning document metadata, which broke downstream filtering in retrieval pipelines. PR #7421 was reviewed and merged by the LangChainJS maintainers.

TypeScriptLangChainJSOpen Source

View

04 / Skills

Stack

Backend

TypeScriptNode.jsNestJSPHP (Laravel)Python

Frontend

ReactNext.jsTailwindSvelte

Infrastructure

GCPAWS (S3 and Lambda)AzureDockerCI/CDVercelPostgreSQLMySQLBigQueryRedis

Architecture and APIs

MicroservicesEvent-drivenDDDCQRSRESTGraphQLWebhooksSDKsJestTDD

05 / Writing

Technical writing

I write about systems-level engineering: the kind of implementation details that most tutorials skip over. These are deep dives into topics I found genuinely confusing, written so they don't have to be.

Jan 2025 8 min read

Writing HTTP Server: Understanding TCP

A deep dive into TCP fundamentals and building an HTTP server from scratch, covering the socket layer most engineers never touch.

Aug 2024 12 min read

How We Transitioned from Blobr to Nginx

A production guide to replacing a managed API gateway with a self-hosted Nginx setup: real tradeoffs, config details, and lessons learned.

View all articles on Medium

06 / Contact

Let's talk.

I am open to senior full stack and backend engineering roles in Berlin and remotely. If you are building something technically interesting and want someone who ships end to end, get in touch.

charafbahria@gmail.com

GitHub github.com/fibii LinkedIn linkedin.com/in/fibii Medium medium.com/@fibii

I build the infrastructure behind great products.