FJ
Firas Jday
Senior Full Stack Engineer & Tech Lead
Production software, shipped solo — architecture → prod.
CDI · senior freelance · MVP builds · French & international
Enterprise platforms and intelligent automations — from architecture to production.
I architect and ship production software end-to-end — enterprise backends (NestJS, Supabase), full-stack products (Next.js, React 19), and AI automations (n8n, LangChain). Whether you need an MVP shipped fast or a senior engineer to lead the build, I take it from architecture to production.
Calling card
Firas Jday
Senior Full Stack Engineer & Tech Lead · Tunis, Tunisia · 5+ yrs
jdfyras@gmail.com · +21629449117
2s → <200ms
marketplace queries, built solo
// Dossier — Subject 01
Positioning
A senior engineer who owns the whole arc — architecture, build, hardening, and the docs that keep it alive.
File: Firas Jday — Profile
Senior Full Stack Engineer & Tech Lead with 5+ years delivering production systems in TypeScript, Node.js, and Python — from fast MVPs to hardened enterprise platforms.
I'm a Senior Software Engineer and Tech Lead with 5+ years delivering production systems in TypeScript, Node.js, and Python — from enterprise transport platforms (NestJS, Supabase, Redis) to intelligent automation workflows (n8n, LangChain, OpenAI). Currently a senior software engineer at Korbyx (ex-Ailéane), where I led the architecture of a fleet-operations platform for a French passenger-transport operator. I've also shipped automation systems for French-market clients on Upwork and built multi-cloud data pipelines at Mercio. Fluent in French, professional working English. Available for CDI and senior freelance engagements.
- Architecting production backends — NestJS, Supabase/PostgreSQL, Redis, REST APIs
- Building real-time systems — live GPS tracking, SSE, WebSockets, event-driven architectures
- Designing enterprise frontends with Next.js, React 19, TanStack Query, and Tailwind CSS
- Delivering intelligent automation workflows (n8n, Zapier, Make) and AI agents (LangChain, OpenAI)
- Engineering cloud data pipelines — GCP, BigQuery, Dataform, Cloud Functions
“I listen to the problem first, then propose the architecture.”
// Index cards — Engagements
How I work with you
Scoped engagements, from a fast audit to a hardened production system.
Automation Audit & Roadmap
Pinpoint exactly where your team is bleeding hours — and leave with a concrete, prioritised plan to reclaim them.
✓ If the audit doesn't surface at least 3 ROI-positive opportunities, it's free.
n8nGoogle WorkspaceAPIsData modeling
Book the audit →n8n Workflow Build & Hardening
Workflows that run every night without waking anyone up — error handling, dead-letter queues, and alerting built in from day one.
✓ Milestone-based (40/40/20) with written acceptance criteria — it runs in production, or I keep working free until it does. 14-day post-launch fix window.
n8nWebhooksPostgreSQLDocker
Scope my workflow →Google Workspace Automation Systems
Transform your Google Sheets from a fragile, manually-maintained file into a reliable, self-updating operational system.
✓ Fixed scope, fixed price, milestone-based — with a 14-day post-launch fix window.
Google Apps ScriptGoogle Sheets APIJavaScriptAPIs
Start a project →AI Agents for Business Workflows
Move beyond the chat demo — build AI that takes real actions: queries your database, calls your APIs, routes decisions, and follows your business rules.
✓ Milestone-based with written acceptance criteria and a 14-day post-launch fix window.
LangChainOpenAI APIPythonVector search
Book a call →Automation Care — Monthly Retainer
Your automations stay alive: monitoring, priority fixes, and new automations every month — so production systems never rot.
✓ Month-to-month — cancel anytime with 30 days' notice.
n8nMonitoringAPIsSupport SLA
Discuss a retainer →Freelance — Upwork
Selected Work
n8n Automation Engineer & AI Agent Architect
n8n automation and AI agents for French-market clients.
Dec 2025 — Jan 2026
Highlights
- Built an n8n SQL orchestrator agent (34 nodes): the model writes the audience-scoring SQL, n8n executes it and returns counts only
- Human validation through Microsoft Teams Adaptive Cards, with step-by-step audience widening
Stack
n8n
LangChain
OpenAI API
Python
Apps Script Algorithm Specialist
High-performance inventory consolidation across 100k+ SKUs and four external data sources.
May 2025 — Aug 2025
Highlights
- Engineered a 64-column calculation engine processing 100k+ SKUs from 4 external sources — completing in under 90 seconds
- Hardened spreadsheet workflows with parameter validation, file-modification tracking, and full audit logging via a LOGS sheet
- Integrated live REST API feeds so data refreshes with a single menu click, replacing slow manual CSV exports
Stack
Google Apps Script
Google Sheets API
JavaScript
Team Lead & React Native Developer
US real-estate marketplace (buyers and sellers without an agent): React Native mobile app and React portal, as de facto technical lead.
Jul 2024 — Nov 2024
Highlights
- Built React Native screens: authentication with access/refresh tokens, document templates with search and audit history, loan pre-qualification flow
- Acted as technical lead: API specs, backend prioritisation, designer interface and hiring of a backend developer
Stack
React Native
React
Python (Flask/FastAPI)
MongoDB
// Photo wall — Selected work
Selected projects
Six shipped systems. Tap a photo for the case study.
Tech Lead · Real-time SaaSTreal-time GPS ops
Transport Ops — Fleet Platform
Technical lead: transport planning, live GPS fleet ops, configurable EU driving-time (RSE) rule engine.
NestJS 11Next.js 16SupabaseRedisEntra ID
Full-Stack Product · MVPA2s → <200ms
Art à Suivre — Marketplace
Complete e-commerce marketplace built solo: 38 NestJS modules, 84 React pages, Stripe, AI recommendations.
NestJS 11React 18PostgreSQLStripeVite
AI & AutomationAI34-node agent
SQL Agent — n8n
An LLM writes audience-scoring SQL; n8n executes it and returns counts only, with validation in Teams.
n8nOpenAIPostgreSQLTeams
Cloud & DataRAzure → BigQuery · Dataform
Enterprise Retail — Data Platform
Azure→GCP pipeline for a retail pricing platform: Cloud Functions load BigQuery, Dataform builds the pricing tables.
PythonGCPBigQueryDataformGKE
Automation & ProductivityG100k+ SKUs <90s
Gestion des Stock — Add-on
64-metric engine over 100k+ SKUs from 4 sources; single-click sub-90s refresh.
Apps ScriptSheets APIclasp
Blockchain & Web3BMerkle-verified mint
Banana NFT — Backend
NFT mint & reveal backend: Merkle proofs verified on-chain, per-user minting cycles, token-ID ranges.
Node.jsExpressSolidityEthers.js
// Stapled CV sheet — Service record
Experience
Firas Jday
CURRICULUM VITÆ · SENIOR FULL STACK ENGINEER & TECH LEAD
Senior Software Engineer — Korbyx (ex-Ailéane)
Feb 2026 - Present
- Architected and delivered a domain-driven NestJS 11 REST API modelling the full transport domain — contracts, service templates, individual courses, and multi-stop driver shifts — on Supabase/PostgreSQL, with a dedicated GPS worker communicating over Redis Pub/Sub
- Designed a DB-driven rule engine for EU driving-time (RSE) and contractual constraints, with a three-level exception system (N1/N2/N3) — business rules configurable by operators without touching code
- Delivered live fleet operations including real-time GPS tracking and SSE streams — with an architectural firewall between the published plan and day-of operations, preventing live changes from corrupting the schedule
- Integrated three external systems (Michelin Connected Fleet GPS/tachograph, PTV routing/ETA, Factorial HR) via scheduled cache tables, keeping the platform fast and available even when third-party APIs are slow or down — with a documented GDPR geolocation register
NestJS · TypeScript · Next.js · Supabase (PostgreSQL) · Redis · TanStack Query · Zustand · MapLibre GL · Microsoft Entra ID · Railway
Senior Automation Consultant (n8n & AI Agents) — Freelance (Upwork)
Dec 2025 - Jan 2026
- Engineered multi-step AI agents with LangChain and GPT-4o that autonomously handle document parsing, data enrichment, and decision routing — eliminating analyst bottlenecks in client operations
- Architected end-to-end n8n orchestrations connecting CRM, email, Slack, and databases — delivering fully autonomous pipelines with error alerting and human-approval checkpoints
- Cut manual data-processing time by 90% through intelligent field extraction, format normalisation, and auto-routing — previously a 3+ hour daily task for the client team
- Deployed RAG pipelines enabling clients to query years of internal documentation and support history in natural language, with source citations and configurable confidence thresholds
n8n · Python · LangChain · OpenAI API · PostgreSQL · Docker
Apps Script Algorithm Specialist — Freelance (Upwork)
May 2025 - Aug 2025
- Engineered a 64-column inventory calculation engine processing 100k+ SKUs across four external data sources — consolidating in under 90 seconds what previously took hours of manual work
- Cut Apps Script execution time by 80% through batch API calls, PropertiesService caching, and lazy-evaluation strategies that prevent hitting Google's execution timeout limits
- Built parameterised Google Workspace Add-ons with ABC classification, dead-stock identification, and automatic sheet templating — replacing a multi-hour weekly consolidation process
- Integrated Google Sheets with live external REST APIs for real-time inventory synchronisation, with file-modification-date tracking and multi-layer validation safeguards
Google Apps Script · JavaScript · Google Sheets API · Data Structures · Algorithms
Software Engineer — Full Stack — Mercio
Jun 2025 - Jan 2026
- Worked on the Java 17/Spring Boot pricing services — Gradle composite build, Keycloak authentication, Liquibase-managed schemas and Cucumber/BDD acceptance scenarios
- Worked on the configurable pricing-rules engine: business teams define prioritised strategies and ordered rules in the UI, without a code deployment
- Containerised services deployed on GKE with Helm, plus a maintenance Cloud Function that resets stuck pods
- Worked on the Azure-to-GCP pipeline: Python Cloud Functions copy source files to Cloud Storage and load BigQuery, Dataform builds the pricing tables, and results sync back to PostgreSQL
Java 17 · Spring Boot · React · GCP · Kubernetes · BigQuery
Senior JavaScript Developer & AI Expert — Cybelle Data
Nov 2024 - Jun 2025
- Built Google Workspace back-office tools: a Google Drive migration app (React, Node.js/Express, Drive API) and a Calendar sync service (Node.js, Firestore)
- Cybelle Flow: a document pipeline on Google Drive (Angular, Express, Firebase) that cut an admin workflow from 4 hours to under 15 minutes
- Migrated legacy VBA tooling to Node.js and Firestore
React · Angular · Node.js · Firestore
JavaScript Developer — Tanitlab AI
Jul 2023 - Oct 2024
- Automated cross-team business workflows in Google Apps Script — consolidating data from 10+ sources, enforcing validation rules, and eliminating 35% of repetitive daily operations
- Deployed production Node.js/PostgreSQL services on Google App Engine with Secret Manager, automated provisioning scripts, and zero-downtime health-check-based deploys
- Built a self-updating BigQuery documentation system that introspects schema metadata and generates structured technical specs — replacing a full sprint cycle of manual documentation work
- Reduced manual data-processing errors by 90% through intelligent validation layers, automated reconciliation pipelines, and real-time exception alerting to the responsible teams
Google Apps Script · Node.js · PostgreSQL · Google App Engine · BigQuery
Full Stack Developer & Team Lead — Booster BC
Sep 2021 - Jun 2023
- Led a 5-engineer team delivering a high-traffic e-tourism platform — owning sprint planning, code review, and core architecture decisions
- Architected distributed microservices (Node.js, Express) with hybrid MongoDB/SQL Server storage and Redis caching for real-time travel search and booking
- Integrated multiple GDS and travel providers (Amadeus, Rakuten Travel Xchange, hotel & flight aggregators) behind unified REST APIs
- Improved booking efficiency by 40% through combined UX and backend optimisation
Node.js · Express · MongoDB · SQL Server · Redis · Docker · Microservices
// Folder dividers — Toolkit
Skills
Grouped by file divider — pick a tab.
Node.jsTypescriptNestJSExpress.jsServerless FunctionsREST APIsPythonFastAPI
React 19Next.jsAngularReact Nativeshadcn/uiRadix UITanStack QueryTypeScriptTailwind CSSMaterial-UI
Google Cloud PlatformAWSAzureBigQueryGKECloud FunctionsCloud StorageFirebaseVercel
n8nZapierMake (Integromat)Google Apps ScriptWorkflow AutomationAPI IntegrationTask SchedulingETL Pipelines
DockerKubernetesHelm ChartsCircleCICI/CDGradleTerraform
PostgreSQLMongoDBBigQuerySQL ServerRedisFirestoreDrizzle ORM
Microsoft Entra IDOAuth2JWTOpenID ConnectRole-based Access Control
LangChainOpenAI APIsAI Agent OrchestrationEthers.jsSoliditySmart Contracts (ERC-721A, ERC-1155)
// Sticky notes — Proof in numbers
The numbers
2s → <200ms
marketplace queries (built solo)
100k+ SKUs <90s
Sheets automation engine
90%
less manual work (n8n + AI)
// Note cards — In their words
What clients say
From Upwork reviews and LinkedIn recommendations.
100% Job Success5.0★ · 10 reviews~11.6K on LinkedIn
★★★★★
“Firas is an absolute gem. Working with him is a breeze as he understands your request and does his best to resolve any issues. We will definitely be using him again in the future”
Upwork clientMisc Development Work (OpenWeb)
★★★★★
“Excellent skills, he fixed my n8n workflow in no time”
Upwork clientn8n automation + AI agent (French client)
★★★★★
“Absolutely superb freelancer. He fixed our problem quickly and efficiently. We highly recommend him.”
Upwork clientNode.js and AI Builder Expert Needed to Recover Crashed Web App (OpenWeb)
★★★★★
“Firas is a reliable Freelancer: very skilled as node.js developer. We well brainstormed the development strategy then he worked in autonomy and efficiently. I'll recommand him and look forward to work with him again.”
Upwork clientSenior Node.js Developer Needed for Project (Tanitlab)
“Firas is a dedicated and passionate developer who becomes unstoppable once he's on a project. As a Senior Full Stack & Cloud Data Engineer specializing in Java, Spring Boot, and modern web technologies, he consistentl…”
Jérémy RochotData Centric Engineer
“Firas is one of the most talented full stack developers I've had the pleasure of working alongside. His technical skills span from Java Spring Boot microservices to React frontends, and he consistently delivered high-…”
Ahmed DalhoumBlockchain Engineer @ Warden Labs | Top Rated Plus Developer
// Stamped seals — Credentials
Certifications
Software Engineer Certificate
HackerRank · Sep 2025
Node.js (Intermediate) Certificate
HackerRank · Jan 2024
BSc Computer Science
ISET Nabeul · 2022
Frequently Asked Questions
Yes — that's a sweet spot. I've shipped full products solo, end-to-end: Art à Suivre is a complete e-commerce marketplace (38 NestJS modules, 84 React pages, Stripe, AI recommendations) with product queries cut from 2s to under 200ms. I take you from architecture to a shipped, documented MVP — then harden it for scale.
Enterprise-grade platforms end-to-end — from NestJS backends and Next.js frontends to data pipelines and real-time systems. My work at Korbyx covers domain modelling, rule engines, live GPS tracking, and multi-process backend architecture for France's regulated passenger-transport sector.
I build production n8n workflows and AI agents — for example an SQL agent whose model writes the query but never touches the database. I also build Google Apps Script engines, LangChain agents, and natural-language-to-SQL systems that put database power in non-technical hands.
Yes — my current role at Korbyx is Tech Lead & Senior Full Stack Engineer, and I'm available for CDI positions or senior freelance engagements. I'm comfortable owning architecture decisions, API contracts, delivery cadence, and cross-team integrations from day one.
Extensively. I've built Apps Script add-ons, Drive/Sheets/Gmail integrations, and GCP data pipelines (Cloud Functions, BigQuery, Dataform, GKE) for enterprise clients — including an Azure-to-GCP data pipeline for a retail pricing platform.
A short discovery call is the fastest path. I listen to the problem first — then propose a concrete architecture or automation roadmap with scope, timeline, and clear deliverables.
Firas Jday
Senior Full Stack Engineer & Tech Lead
Have a real domain problem to solve? Let’s talk architecture — not just technology.
A short discovery call is the fastest path. I listen to the problem first, then propose a concrete architecture or automation roadmap.
— or reach me directly —