Freelance

Four fixed-price services you can order straight away on Fiverr or Upwork, or talk through on a paid consultation call first.

§1BigQuery data pipelines with Airflow and dbt on Google Cloud

Production-grade BigQuery pipelines your analysts can trust, without hiring a full-time data team. I spent five years on telco data platforms: Vodafone Hungary's analytics migration to Google Cloud and Deutsche Telekom's sovereign Apache Iceberg lakehouse on GCP, both covered by public Google Cloud case studies.

Diagram: APIs, databases, files, GA4 and SaaS tools flow into raw, staging and marts layers in a warehouse, each tested and orchestrated daily by Airflow, then on to dashboards, ML models and apps. — Figure 1. Listing cover on Fiverr and Upwork.

Starter Pipeline: 1 source into BigQuery, a tested dbt model, daily schedule and a short handover doc
Production Pipeline: Up to 3 sources, Airflow DAGs, dbt staging to marts with tests, alerting and documentation
Data Platform: Up to 6 sources, lakehouse on BigQuery and GCS or Iceberg, CI/CD, data quality, cost tuning

Table 1. Packages and what each one includes.
Package	Starter Pipeline	Production Pipeline	Data Platform
Price	$450	$1,050	$2,100
Delivery	3 days	7 days	14 days
Revisions	1	3	5
Package	1 source into BigQuery, a tested dbt model, daily schedule and a short handover doc	Up to 3 sources, Airflow DAGs, dbt staging to marts with tests, alerting and documentation	Up to 6 sources, lakehouse on BigQuery and GCS or Iceberg, CI/CD, data quality, cost tuning
Tables / models	3	9	18
Source code	included	included	included
Data source connectivity	included	included	included
API integration	included	included	included
Formatting and clean-up	included	included	included
Documentation	included	included	included
Data quality checks	included	included	included
Unit tests	not included	included	included
Orchestrator setup	not included	included	included

Extras

Extra-fast delivery+$150 / +$300 / +$600 (Starter Pipeline / Production Pipeline / Data Platform)
Additional data source+$100
Additional table or model+$100
Looker Studio dashboard+$200
Terraform for the setup+$200
Extra revision+$50

Fiverr and Upwork each cap how many extras a listing can have, so a few are only on one of them. If the one you need is missing, message me and I'll send a custom offer.

You own all code. EU-based, GDPR-aware, NDA on request. Please message me before ordering so I can confirm your sources and scope.

Order on Fiverr ↗Order on Upwork ↗

What I build

Ingestion from APIs, databases, files, GA4, ads and SaaS tools into BigQuery
Orchestration with Apache Airflow or Cloud Composer
dbt models (staging, intermediate, marts) with tests and docs
Medallion and lakehouse layouts on GCS, BigQuery and Iceberg
Data quality checks, alerting and CI/CD (GitLab or GitHub)
Cost tuning: partitioning, clustering, query optimization

How I work

You share goals, sources and access to your own GCP project.
I confirm the scope with a simple architecture diagram.
I build, test and document in your repository.
Handover call and a written runbook.

Listing details

Category: Data › Data Engineering › Data ETLs
Expertise: Data pipelines, ETL development, Data warehousing, Data lake setup, Data modeling
Technology: Google BigQuery, Apache Airflow, dbt, Google Cloud Storage, Google Dataflow
Stack: [bigquery][airflow][cloud composer][dbt][apache iceberg][gcs][terraform][looker studio]
Tags: bigquery, data engineering, airflow, dbt, google cloud

Frequently asked questions

What do I need to provide?

A GCP project with billing, IAM access for me, credentials for each source and a short description of the questions the data should answer.

Who pays the Google Cloud costs?

You do, in your own project. I design for low cost (partitioning, incremental models) and estimate the monthly spend at handover.

Do I get the code?

Yes. Everything lives in your Git repository: pipelines, dbt project, docs and runbook.

Can you work with Snowflake, Databricks or DuckDB?

Yes, but Google Cloud is my specialty. Message me with your stack and I'll confirm before you order.

How do you handle sensitive data?

Least-privilege access, no data copied outside your project, NDA on request. I'm EU-based and used to GDPR-bound telco data.

What counts as a revision?

Changes within the agreed scope. New sources or new models are extras or a custom offer.

I only need an audit of my current setup.

Message me: I offer a 3-day architecture, cost and reliability audit with a prioritized roadmap as a custom offer.

What I'll ask when you order

What business questions or reports should this data support?
Your data sources: type, approximate volume and access method (API, database, files).
Is your GCP project ready, can you grant IAM access, and in which region?
Which tools are already in place (Airflow, dbt, Looker, Git provider)?
Any personal or sensitive data, deadlines or compliance constraints?

§2Custom AI agents and RAG apps on your company data

An AI agent that works on your data, not just a demo: it answers from your documents, uses your tools and stays reliable in production. I'm co-founder and CTO of an AI-native engineering lab in Vienna and a data engineer with five years on telco data platforms, so my agents are built like data products: tested, logged and cost-controlled.

Diagram: your docs, website, CRM and database feed an agent running on Claude, GPT or Gemini that finds the right passages, reasons over them and acts with your calendar, email, Slack and APIs, with a sample answer that cites its source. — Figure 2. Listing cover on Fiverr and Upwork.

Agent Prototype: Scoping plus a working prototype: 1 agent or RAG app over your docs or 1 data source
Production Agent: Agent or RAG app with up to 3 integrations, evals, guardrails, logging and deployment
Agent System: Multi-step or voice agent, up to 6 integrations, monitoring, cost dashboard and handover

Table 2. Packages and what each one includes.
Package	Agent Prototype	Production Agent	Agent System
Price	$450	$1,050	$2,100
Delivery	3 days	7 days	14 days
Revisions	1	3	5
Package	Scoping plus a working prototype: 1 agent or RAG app over your docs or 1 data source	Agent or RAG app with up to 3 integrations, evals, guardrails, logging and deployment	Multi-step or voice agent, up to 6 integrations, monitoring, cost dashboard and handover
Model integration in your app	included	included	included
Source code	included	included	included
Database integration	not included	included	included
Detailed code comments	not included	included	included

Extras

Extra-fast delivery+$150 / +$300 / +$600 (Agent Prototype / Production Agent / Agent System)
Additional tool or integration+$100
Additional language+$50
Voice channel (ElevenLabs)+$200
AI model fine-tuning+$400
Extra revision+$50

Fiverr and Upwork each cap how many extras a listing can have, so a few are only on one of them. If the one you need is missing, message me and I'll send a custom offer.

You own the code and your API keys. EU-based and GDPR-aware. Please message me first with your use case.

Order on Fiverr ↗Order on Upwork ↗

What I build

RAG assistants over your documents, website or knowledge base
Agents that use tools: CRM, database, email, Slack, calendars, APIs
Voice agents (ElevenLabs) for bookings and support
Agents that safely query your data warehouse (BigQuery, Postgres)
Evaluation sets, guardrails, monitoring and cost dashboards

How I work

We define the use case and what good answers look like.
I build a prototype on your real data.
I harden it: evals, guardrails, deployment.
Handover with docs and a walkthrough.

Listing details

Category: Programming & Tech › AI Development › AI Integrations
AI engine: Claude, ChatGPT / OpenAI, Gemini, LangChain
Programming language: Python, TypeScript
Stack: [python][typescript][claude][openai][gemini][langchain][supabase][elevenlabs]
Tags: ai agent, rag, llm, ai automation, langchain

Frequently asked questions

Which AI models do you use?

Claude, OpenAI, Gemini and Grok by default; open-weight models when data must stay on your infrastructure. I pick per use case and cost.

Who pays for API usage?

You do, with your own API keys and accounts. I estimate the monthly usage cost before we start.

What if the agent gives a wrong answer?

Answers are grounded in your content, tested on an evaluation set, refuse when unsure and can hand over to a human.

Is my data safe?

Your data stays in your accounts. EU hosting options, no training on your data, NDA on request.

What do you need to start?

The use case, sample documents or data access, the tools to connect and 10–20 example questions with good answers.

Do I get the source code?

Yes, in your repository, with setup instructions.

Can you improve an agent I already have?

Yes: I can audit it, build evals and fix reliability issues. Message me for a custom offer.

What counts as a revision?

Changes within the agreed scope. New integrations or channels are extras.

What I'll ask when you order

The use case, and who will use the agent.
What data or documents it should use, and how I can access them.
Which tools or systems it must connect to.
Preferred AI provider and hosting (or no preference), and whether you'll provide API keys.
Which languages the agent should speak.
Any privacy constraints.
10–20 example questions with ideal answers.

§3Location intelligence and site selection with Python, H3 and web maps

Where should you open, invest or expand? I turn location data into clear answers: scored sites, explainable models and interactive maps you can share. I built geospatial ML features and network-planning maps for a national telco's B2B clients, and a Budapest rent model on Uber H3 hexagons with Sentinel-2 greenness and WorldPop population data (9.8% median error on 50,000 listings).

Cover: “Location intelligence on H3 hexagons” over a hexagon grid; site selection, web maps and explainable geo ML with Python, H3, GeoPandas and Leaflet. — Figure 3. Listing cover on Fiverr and Upwork.

Location Snapshot: 1 area, up to 3 open data layers on an H3 grid, interactive map, data files and findings note
Site Selection: Up to 10 sites, 8 location features, explainable scoring, web map, notebook and slides
Geo ML + Live Map: Client + open data pipeline, predictive model with SHAP explanations and a hosted web map

Table 3. Packages and what each one includes.
Package	Location Snapshot	Site Selection	Geo ML + Live Map
Price	$450	$750	$1,050
Delivery	3 days	5 days	7 days
Revisions	1	3	5
Package	1 area, up to 3 open data layers on an H3 grid, interactive map, data files and findings note	Up to 10 sites, 8 location features, explainable scoring, web map, notebook and slides	Client + open data pipeline, predictive model with SHAP explanations and a hosted web map
Maps	1	3	5
Presentation slides	not included	included	included

Extras

Extra-fast delivery+$150 / +$300 / +$300 (Location Snapshot / Site Selection / Geo ML + Live Map)
Additional area or city+$200
Additional data source+$100
Deployment and hosting setup+$100
Scheduled data refresh+$200
Client-ready slide deck+$100
Extra revision+$50

Fiverr and Upwork each cap how many extras a listing can have, so a few are only on one of them. If the one you need is missing, message me and I'll send a custom offer.

EU-based. Please message me before ordering so I can check data availability for your area.

Order on Fiverr ↗Order on Upwork ↗

What I build

Site selection and catchment analysis (population, competitors, POIs, travel-time isochrones)
H3 hex-grid location features ready for machine learning
Satellite and open data: Sentinel-2, WorldPop, OpenStreetMap, Eurostat
Explainable scoring and predictive models (XGBoost, SHAP)
Interactive web maps (Leaflet, kepler.gl) with automated data refresh
Real estate location analytics: rent, yield, neighbourhood quality

How I work

You tell me the decision, the area and any sites or customer data you have.
I check open data availability for your area before you order.
I build the features, scores or model and the map, in reproducible code.
You get the map, notebooks and data files in open formats (GeoParquet, GeoJSON, CSV).

Listing details

Category: Data › Data Visualization › Geographic Information Systems (GIS)
Tool: Python
Stack: [python][geopandas][h3][rasterio][osmnx][duckdb spatial][bigquery gis][postgis][leaflet]
Tags: geospatial, spatial analysis, python, site selection, leaflet

Frequently asked questions

What data do I need?

Your locations or customer data if you have them. I source open data: OpenStreetMap, WorldPop, Sentinel-2, Eurostat and national statistics.

Which areas can you cover?

Anywhere with good open data; Europe is strongest. I confirm data availability for your area before you order.

Do I get the code and data?

Yes: notebooks, scripts and outputs in GeoParquet, GeoJSON and CSV.

Can the map be embedded on my website?

Yes, as an embeddable web map, or hosted on your own cloud with the deployment extra.

Can you refresh the data regularly?

Yes, with the scheduled data refresh extra; ongoing hosting can be arranged as a custom offer.

How do you handle customer location data?

It stays in your accounts and is used only for the project. EU-based, NDA on request.

What counts as a revision?

Changes within the agreed area, layers and features. New areas or data sources are extras.

What I'll ask when you order

What decision should the analysis support (site choice, investment, expansion, planning)?
Which area or areas, and your candidate sites or customer locations if you have any.
What data you have (format, size), and what I should source.
Preferred output: report, interactive map, model, or all three; and whether to embed it on a website.
Deadlines and data-privacy constraints.

§4Custom business websites with booking and an AI chatbot

A fast, professional website that does more than look good: it takes bookings, sends emails and can answer your clients with an AI assistant. Pick the level you need — Launch gets a fast, accessible site with SEO live in one day; Grow adds a backend with a custom booking calendar, contact-form emails and editable content; Automate adds an AI assistant that answers from your content and books appointments.

Cover: “Live in 1 day — fast, bilingual, accessible” beside a laptop and a phone showing the bilingual website of a sport psychologist. — Figure 4. Listing cover on Fiverr and Upwork.

Launch: Fast site with 3 menu sections, SEO and social meta, accessible, deployed live
Grow: Up to 4 pages plus backend: custom booking calendar, contact form with email, editable content
Automate: Everything in Grow plus an AI assistant that answers from your content and books appointments

Table 4. Packages and what each one includes.
Package	Launch	Grow	Automate
Price	$150	$450	$1,050
Delivery	1 day	3 days	7 days
Revisions	1	3	5
Package	Fast site with 3 menu sections, SEO and social meta, accessible, deployed live	Up to 4 pages plus backend: custom booking calendar, contact form with email, editable content	Everything in Grow plus an AI assistant that answers from your content and books appointments
Pages	3	4	6
Integrations (email, calendar, analytics…)	0	3	4
Content upload	included	included	included
Opt-in form	not included	included	included
Autoresponder (booking and contact confirmations)	not included	included	included
Speed optimization	included	included	included
Hosting setup	included	included	included
Social media icons	included	included	included

Extras

Extra-fast delivery– / +$150 / +$300 (Launch / Grow / Automate)
Additional page+$50
Additional language (you provide the text)+$100
GDPR pack (privacy page, cookie consent)+$50
Stripe payments for bookings+$200
Domain and email DNS setup+$50
Extra revision+$50

Fiverr and Upwork each cap how many extras a listing can have, so a few are only on one of them. If the one you need is missing, message me and I'll send a custom offer.

Clean code you own, hosted on your own accounts. Please message me before ordering with your goals and any example sites you like.

Order on Fiverr ↗Order on Upwork ↗

What I build

Multilingual sites: English, German, Hungarian, Spanish
Custom booking calendars that sync with Google Calendar or cal.com
Contact forms with email confirmations and reminders
Content you can edit yourself in an admin panel
AI assistants that answer only from your content and hand over to you
Accessibility, performance and SEO built in; EU hosting options

How I work

You send your goals and 2–3 websites you like.
I confirm the package and what I need from you: logo, texts, photos, services.
I build the site and share a preview for your feedback.
I go live and hand over the repository and admin access to every account.

Listing details

Category: Programming & Tech › Website Development › Custom Websites
Website type: Business
Programming languages: TypeScript, React, Tailwind CSS, Node.js, JavaScript
Website features: Booking, Calendar, Form, Chat, Customer support, User authentication, Admin panel, Landing page, Portfolio, FAQ
Stack: [react][typescript][tanstack start][next.js][tailwind][supabase][cloudflare]
Tags: custom website, website development, react website, booking system, ai chatbot

Frequently asked questions

Who pays for hosting, the domain and AI usage?

You do, on your own accounts (typically a few euros a month; AI usage depends on traffic). I set everything up for you.

Do I own the code?

Yes. You get the repository and admin access to every account.

Can the booking sync with Google Calendar?

Yes. Bookings can sync with Google Calendar or cal.com, with email confirmations and reminders.

What if the AI assistant answers wrongly?

It only answers from your content, refuses when unsure and hands over to you by email.

Which languages can my site have?

Any; I work in English, German, Hungarian and Spanish. Extra languages are an extra.

Is it GDPR compliant?

I use EU hosting regions and can add a privacy page and cookie consent with the GDPR extra. Legal text review is your lawyer's job.

What do you need to start?

Your logo, texts, photos, services and 2–3 websites you like. No texts yet? Tell me and we plan around it.

What counts as a revision?

A round of changes to the delivered design or content within the package scope. New pages or features are extras.

Can you redesign my existing website?

Yes. Send me the link and I'll confirm the right package.

What I'll ask when you order

What the website is for, and who your visitors are.
Your logo, texts, photos and list of services (or what's still missing).
2–3 websites you like, and what you like about them.
Whether you already have a domain and hosting, and which languages you need.
For Grow and Automate: how bookings should work (services, durations, availability, calendar); for Automate, which documents or FAQs the assistant should use.

§5Consultation call

Not sure which package fits, or want a second opinion before you commit? Book a paid consultation on Upwork and we'll go through your data, AI or website plans together. Upwork shows the length and price when you book.

Book on Upwork ↗

§6Freelancer profile

For longer engagements or work outside these packages, you can also hire me through my freelancer profile on Malt.

malt.com/profile/balintdecsi ↗

All gigs and reviews on Fiverr: fiverr.com/balint_decsi ↗