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Igor A.

Salvador, Brazil

$90/hr
4.9
69 jobs

I help companies design, build, and scale production-ready AI systems — LLM applications, RAG platforms, AI agents, NLP pipelines, machine learning models, workflow automations, and full-stack AI products. I’m an Expert-Vetted Upwork freelancer, ranked in the Top 1% of talent on the platform, with 12+ years of experience across AI, Data Science, Machine Learning, GenAI, NLP, MLOps, automation, and product engineering. On Upwork, I’ve delivered $400K+ in client work, 60+ jobs, and 8,600+ hours for startups, enterprises, and global clients. My strongest fit is with teams that need more than a prototype. I help clients move from idea to architecture, from architecture to implementation, and from implementation to reliable AI products that can be used in real business workflows. What I can help you build • LLM-powered applications, copilots, and AI assistants • Retrieval-Augmented Generation, or RAG systems • AI agents for research, automation, decision support, and internal operations • Chatbots connected to private company data, documents, and knowledge bases • NLP pipelines for classification, summarization, extraction, matching, and search • Semantic search and embedding-based recommendation systems • Fine-tuning, model evaluation, prompt engineering, and LLM workflow optimization • Machine learning models for prediction, forecasting, clustering, ranking, and anomaly detection • AI automations using Python, APIs, databases, cloud tools, vector databases, and orchestration layers • Technical architecture for AI SaaS products, internal tools, and AI operating systems Why clients work with me I combine senior AI leadership with hands-on technical execution. I can speak with executives about business value, work with product teams on scope and roadmap, and collaborate with engineers on architecture, implementation, deployment, and long-term maintainability. My background includes enterprise AI and Data Science work for companies such as HEINEKEN, Korn Ferry, and SKF, plus 60+ consulting projects across multiple industries and countries. I’ve led Data Science and AI initiatives, built production ML systems, designed GenAI and RAG solutions, and worked across both strategic AI adoption and hands-on engineering. I’m also a founder and full-stack product builder. As the founder, CEO, CTO, and solo developer of Vivai, I built a marketplace platform end to end, including mobile app, backend APIs, PostgreSQL database architecture, search, payments, authentication, partner workflows, cloud deployment, and production operations. Example projects I can support • Build a custom AI assistant over your company documents • Create a RAG system with retrieval quality, evaluation, monitoring, and guardrails • Automate business workflows using LLMs, APIs, scheduled jobs, and human-in-the-loop review • Improve an existing AI product for accuracy, reliability, speed, and cost • Develop NLP classification, extraction, summarization, or semantic search systems • Design the architecture for an AI SaaS product or internal AI platform • Turn a rough AI prototype into a stable, maintainable production system I’m a good fit if you need someone who can understand the business problem, recommend the right AI architecture, and build a practical solution with clean, maintainable implementation. If your goal is to build real AI products — not just demos — I can help you get there.

  • R
  • Python
  • Natural Language Processing
  • SQL
  • Data Visualization
  • Natural Language Generation
  • Machine Learning
  • Deep Learning
  • Data Science
  • Transformer Model
  • GPT-4
  • ChatGPT
  • GPT-3
David O.

Pulaski, New York

$58/hr
4.8
70 jobs

I turn messy, high-stakes data into decisions people can act on. Over 15+ years and 66 Upwork contracts (~4.9/5 stars across rated jobs, 84% perfect 5.0s), I've built my practice on one promise: you get a clear answer, a tool your team can actually use, and plain-English communication throughout. What I do best: * Interactive R Shiny dashboards and analysis platforms: 12+ shipped, including a 20+ package bioinformatics platform and a no-code causal-inference tool for pharmaceutical analysts * Machine learning and predictive modeling: injury prediction for an NFL franchise, mortgage default risk, game simulation * Statistical analysis: hierarchical Bayesian modeling, MaxDiff and survey analytics, meta-analysis, causal inference * R package development: a production package built over a 952-hour flagship engagement, plus a released CRAN package * Quantitative finance: DCC/GARCH modeling, asset allocation, backtesting frameworks Domains I know well: healthcare and EHR data, bioinformatics and genomics, finance and trading, marketing analytics, survey research, and sports. How I work: independently, end to end. Most clients hand me a problem, not a spec. I scope it, deliver in agreed milestones, and explain the results so non-technical stakeholders can make the call. That approach is why most of my work is repeat business, and why "Committed to Quality" and "Clear Communicator" are my two most-endorsed client tags. M.S. in Bioinformatics from Johns Hopkins. Co-author on 8 peer-reviewed papers. US-based native English speaker. If you have data that should be driving a decision and isn't yet, let's talk.

  • R
  • Data Science
  • Data Visualization
  • Machine Learning
  • Plotly
  • Data Scraping
  • Quantitative Analysis
  • Bioinformatics
  • Analytics
  • Statistics
  • Forex Trading
  • API
  • R Shiny
  • Data Analysis
Zohal Z.

Canberra, Australia

$65/hr
5.0
109 jobs

🏆 Microsoft Certified: Power BI Data Analyst Associate (PL-300) & Fabric Analytics Engineer Associate (DP-600) Top Rated | 100% Job Success | 90+ Projects Delivered I help businesses automate financial reporting and build Power BI dashboards that provide accurate, real-time insights for better decision-making. With a background in Accounting and Data Science, I design scalable reporting solutions using Power BI, Microsoft Fabric, Excel, SQL, and Python. Services Power BI & Microsoft Fabric dashboards Financial reporting, budgeting & forecasting DAX, data modeling & Row-Level Security Excel automation (VBA & Power Query) API, SQL & cloud data integration Recent Results Reduced month-end reporting from 5 days to 3 hours Built Excel automation saving 10+ hours per week Delivered real-time executive dashboards connected to live data Tools: Power BI | Microsoft Fabric | Excel | DAX | Power Query | SQL | Python | Power Automate | Xero If you're looking for a consultant who understands both finance and analytics, I'd be happy to help. Send me a message to discuss your project.

  • R
  • Data Analysis
  • Microsoft Excel
  • Python
  • SQL
  • Microsoft Power BI
  • Microsoft Power BI Data Visualization
Genadiy R.

Batumi, Georgia

$50/hr
4.9
768 jobs

I help businesses automate their workflows, connect different systems into one ecosystem, and build custom software that saves time. I'm a Senior Full-Stack Developer with 30+ years of software development experience, specializing in web applications, AI integrations, business automation, APIs, and custom internal systems. Whether you need a web platform, a mobile app, an AI-powered assistant, or complex integrations between multiple services, I build solutions that are scalable and designed for long-term growth. A lot of my work also focuses on building practical solutions using APIs, Google Sheets, and AI tools. What I build: Full-stack web applications Business automation platforms Automating business workflows AI-based tools (ChatGPT, OpenAI, Whisper, AI Agents, etc.) API integrations for connecting APIs between different platforms SaaS products, web applications, and backend systems CRM & ERP integrations Internal business systems and admin panels Admin dashboards, reporting & analytics systems Mobile applications (Flutter, AppSheets) Google Workspace & Google Sheets automation E-commerce integrations Frontend: React, Next.js, JavaScript, TypeScript, HTML, CSS Backend: Node.js, Python, PHP, Google Apps Script Databases: MySQL, PostgreSQL, SQL Server, MongoDB, Firebase Cloud & APIs: REST APIs, GraphQL, OAuth, Webhooks, Google Cloud, AWS AI: OpenAI API, ChatGPT integrations, AI assistants, LLM-based workflows, speech-to-text solutions (Whisper) I've built integrations with platforms including: Shopify • Stripe • QuickBooks • HubSpot • Salesforce • GoHighLevel • Zoho • Twilio • Meta/Facebook • Google Workspace • Trello • Pipedrive • Mailchimp • Telegram • WhatsApp • Airtable • Notion • and many others. I prefer simple, safe solutions that solve real business problems. In most cases, I choose custom development over no-code tools because it gives more flexibility and long-term stability. I'm available for both short-term projects and long-term partnerships involving: • Full-stack web development • Business process automation • AI implementation • API integrations • SaaS development • Mobile applications • System architecture • Internal business platforms

  • Web Development
  • Mobile App Development
  • Automation
  • AI App Development
  • Python
  • React
  • Node.js
  • TypeScript
  • Google Apps Script
  • JavaScript
  • Google Cloud Platform
  • OCR Algorithm
  • Apps Script API
  • Google Chrome Extension
  • Google Sheets
  • Google APIs
  • Excel Macros
  • ChatGPT
  • Flutter
Miguel R.

Homestead, Florida

$20/hr
4.7
948 jobs

I have been a lead generation specialist for over 20 years. My skill set is very well rounded which allows me to specialize in finding qualified leads for businesses, organizations and individuals. My services are included – ►Lead Generation ►B2B Sales lead Generation ►Prospect List Building ►Contact List Building ►Data Collection ►Web Research ►LinkedIn Data Research ►Data Entry ►Email List Building ►Company Data Research ►Database Creation ►Data Mining ►Web Scraping ►Data Extraction ►Data Accuracy Verification ►Administrative Support Task ►PDF Conversion I have spent years helping various companies by providing my best services whether it is lead generation, list building. I always try to satisfy my client and complete the job on time.

  • Lead Generation
  • Data Entry
  • Data Mining
  • Data Scraping
  • List Building
  • Microsoft Excel
  • Online Research
  • LinkedIn
  • B2B Lead Generation
  • LinkedIn Sales Navigator
  • Administrative Support
  • Prospect List
  • Data Extraction
  • Company Research
  • PDF Conversion
ahmad K.

Ghobeiry, Lebanon

$45/hr
4.9
189 jobs

Data Scientist & Statistician of experience in R, Python, SPSS,Excel،Power BI and SQL. I specialize in machine learning, predictive modeling, biostatistics, clustering, classification, and data visualization. R Packages: tidyverse, tidymodels, dplyr, ggplot2, caret, randomForest, glmnet, xgboost, nnet, lme4, forecast, data.table, readr, stringr, Shiny, Quarto, R Markdown and much more Python Packages: pandas, numpy, scikit-learn, statsmodels, matplotlib, seaborn, plotly, TensorFlow, Keras, PyTorch, XGBoost, LightGBM, CatBoost. Other Tools: SPSS, SAS, Minitab,Power BI, PASS, Microsoft Excel/Office, SQL, Power BI etc... I deliver clean, reproducible, and decision-ready analytics — from statistical modeling and survey analysis to machine learning pipelines and dashboards.

  • R
  • Microsoft Excel
  • Data Science Consultation
  • SAS
  • Data Science
  • Statistical Analysis
  • Statistical Programming
  • Statistics
  • R Shiny
  • RStudio

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Don't just take our word for it

R vs. Java vs. Python: Which Is Right for Your Project?

When it comes to data science, there’s no one best programming language. There are a few standouts, however, each with its own specialties, as well as packages, libraries, and extensions that further enhance their capabilities.

In this article, we’re going to take a closer look at three of the most popular languages used by data scientists: Java, Python, and R. You’ll learn the basics of each, as well as how to tell which one is right for your data needs.

R: beloved by data scientists

Originally developed by statisticians as an open-source alternative to expensive suites of statistical software like SAS and MATLAB, R is one of the most popular languages for data analysis. It’s been likened to Excel on steroids, able to sift through reams of data, execute sophisticated analyses, and produce publication-quality graphs and tables. What makes R special? In short, it’s a tool built with data analysis in mind.

As data science has become critical to many businesses, R’s popularity has skyrocketed. Organizations as large and diverse as Google, Facebook, Microsoft, Bank of America, and the National Weather Service have all turned to R for reporting, analysis, and visualization.

A key component of R is that, unlike object-oriented programming languages like Java or Python, R is a procedural language, meaning it relies on a series of step-by-step subroutines to execute a programming task. The key difference here is that R uses procedures to operate on data, where object-oriented programming bundles procedures and data together as parts of objects. The advantage of procedural programming is that it gives clear visibility into complex operations with lots of dependencies, which can be important for many data analysis tasks. The tradeoff is that this often requires more lines of code than object-oriented languages.

Another benefit of R? It’s supported by a vibrant community of developers, especially academic statisticians and data scientists.

Java: speed at scale

Java is powerful, portable, and scalable, which makes the platform perfect for building enterprise-scale applications and supporting rapid growth. Java also includes many tools, collectively known as the Java Platform. This robust, open-source development environment includes libraries, frameworks, APIs, the Java Runtime Environment, Java plug-ins, and the Java Virtual Machine (JVM). Taken together, these tools simplify coding with Java and support development at every level, giving developers everything they need to build Java web systems and applications.

Java’s speed allows it to outperform other languages and frameworks, which is a big part of why it’s so well suited to large-scale applications. These performance gains are what prompted Twitter to shift its search engine to Java from Ruby on Rails and move more of its back-end stack to the Java Virtual Machine.

Another key component of Java is that it comes as close to being 100% object-oriented as you can get. With that comes all the benefits of object-oriented programming, from ease of development to modular software to flexibility and extensibility. As one of the most widely known programming languages, it’s easy to find and hire talented developers. What’s more, Java’s massive community of developers means that there’s lots of excellent documentation around.

Python: built for flexibility

Like Java, Python is built to handle high-traffic sites. It’s fast and efficient, with an emphasis on code readability. Python’s motto is “there should be one—and preferably only one—obvious way to do it.” That can mean there’s a bit of a learning curve as developers learn the ins and outs of Python syntax, but the upside is an ability to express concepts with fewer lines of code than would be possible in languages like C++ or Java.

Python’s other great strength is an extensive set of libraries that allow it to perform a wide array of tasks. In particular, the libraries NumPy and matplotlib enable Python to perform many of the analysis and plotting functionalities of MATLAB. These libraries have since been built upon by a number of other libraries that extend Python’s functionality even further.

In short, Python represents a compromise between R and Java, combining the sophistication of the former with the speed and scalability of the latter.

Which language is right for your data needs?

The short answer is that it depends on the kind of work you’re trying to do. A good rule of thumb might be if your work is closer to mathematics and statistics, R is probably your best bet. If your work is closer to programming, go with Python, and if you’re building enterprise-size products, take a look at Java. That said, many data scientists are increasingly turning to combinations of languages that allow them to take advantage of the individual strengths of each.

R

Great For:

  • In-Depth Statistical Analysis. Given that R was developed by and for statisticians, it’s no surprise that R is ideally suited to in-depth statistical analysis, whether you’re working with sensor data from an IOT device or elaborate financial models. What’s more, it’s very well supported by the statistics community through the CRAN repository, which contains literally thousands of packages that enable you to perform more elaborate analysis and visualization tasks.
  • High-Quality Reporting. Well-produced images convey more than numbers alone, and R places a great emphasis on easily producing high-quality graphs and charts. On top of that, its basic capabilities can be extended with a number of packages, including ggplot2, ggvis, googleVis, and rCharts. The Shiny framework also allows you to turn those visuals into interactive web applications.

Not Great For:

  • Performance. R was designed with data scientists in mind, not computers. As such, R is considerably slower than Python or Java.
  • Creating large-scale data products. In these instances, data scientists will often prototype in R and then switch to a more flexible language like Java or Python for actual product development.
  • Ease of Learning. If your background is in math or statistics, R’s array-oriented syntax can make implementation relatively straightforward. If you have programming experience, however, this approach is likely to seem counterintuitive.

Java

Great For:

  • Excellent Performance on Large-Scale Systems. Java’s speed makes it best for building large-scale systems. While Python is significantly faster than R, Java provides even greater performance than Python. Speed and scalability are why Twitter, LinkedIn, and Facebook rely on Java as the backbone of their data engineering efforts.
  • Faster Development Time. The Java Virtual Machine (JVM) is a great environment for developing custom tools quickly. The programming language Scala runs on JVM and is popular with data scientists for its combination of object-oriented and functional programming.

Not Great For:

Statistical modeling and visualization. Between these three languages, Java is definitely the least suited to hardcore analysis. Though packages do exist to add some of these functions, they’re neither as advanced nor as well supported as the ones you’ll find for Python and R.

Python

Great For:

  • Workflow Integration. Python’s flexibility makes it a popular choice for developers who need to apply statistical techniques or data analysis in their work, or for data scientists whose tasks need to be integrated with web apps or production environments. If you’re looking for a single tool to manage your entire data-related workflow, Python is a great option.
  • Machine Learning. The combination of specialized machine learning libraries (like scikit-learn, PyBrain, and TensorFlow) and general purpose flexibility makes Python uniquely suited to developing sophisticated models and prediction engines that plug directly into the production system.

Not Great For:

  • Highly specialized data tasks. Though the Python community is catching up, there are still hundreds of R packages that have no Python equivalents. If you’re looking for very specific capabilities, you might be better off with R.

Hiring a data scientist?

Now that you understand the differences between some of the major languages in data science, who do you need to set up and maintain your data infrastructure? Data scientists come from a variety of backgrounds. Some specialize more in performing statistical analysis, while some are more focused on building products that interface directly with production systems. Explore data scientists on Upwork.