European Summer of Code

Funding stipends for contributors new to open source worldwide, and matching applied AI projects in Europe with international open source projects.

What is European Summer of Code?

European Summer of Code (ESoC) funds stipends for contributors new to open source, and matches open source projects and applied AI projects throughout Europe. We are much indebted to the Google Summer of Code for inspiration.

For Junior Developers

Providing opportunities to engage with open source worldwide

Work with experienced mentors
Build your portfolio
Receive stipends for your work
Join a community of like-minded developers

For Open Source

Linking the worldwide open source landscape with private and public sector projects

Connect with applied projects and sponsors
Increase visibility for your project
Receive support for your ecosystem
Expand your contributor base

For Applied Projects

Providing support to the wider open source ecosystem

Connect with relevant open source projects
Find talented developers
Accelerate your development
Contribute to the open source community

Program Details

Learn how European Summer of Code works for applicants, projects, and sponsors.

Applicant Guide

How to apply for European Summer of Code 2025

Projects

2025 projects are released in three batches: March 27, April 10, and April 25. Projects have their own timelines and may come with their own terms of conditions.

Application Process

Applicants need to do two things to apply:

1
2
Follow Project-Specific Steps
Follow any additional 'how to apply' steps from the project card of your preferred projects.
3
Meet Deadlines
Complete both steps before the project application deadline or batch deadline.
4
Wait for Results
You will receive a letter from ESoC on your application(s) no later than 6 weeks after the application deadline.

Recommendations

Ensure your submitted email address is correct, use the same name and email throughout the process, and submit early to avoid technical issues close to deadlines.

Project and Sponsor Guide

How to participate as a project or sponsor

Onboarding Process

Private and public sector organizations wishing to host a project should submit a project sponsor form. Open source projects should directly contact our LinkedIn organization. Contact us on LinkedIn.

Funding Models

Choose between two funding models:

1
Option A: Donation for Stipend
You donate to a hub, and the hub contracts with the participant. The 'stipend' requires that a significant portion of the outputs are in the open domain.
2
Option B: Paid Internship
You can use your own contract template, in this case the hub will only act as matchmaker, and you will directly contract with applicants.

Project Card

Project cards should include: project title, logos, description, goals, organization info, technical details, application instructions, and deadlines.

ESoC Hubs

The organizational structure of European Summer of Code

Current Hubs

ESoC is organized in a decentral and distributed fashion, by hubs across Europe:

Hub Network

Current hubs include:

Program Timeline

Key dates and milestones for the European Summer of Code 2025 program.

2025, on a rolling basis!
Project release
New projects released continuously!
ProjectsAnnouncement
T+3 weeks
Application Deadline
Deadline to apply - by project.
DeadlineApplications
T+4/5 weeks
Interviews and Selection
Interviews and selection with the project.
InterviewsSelection
T+6 weeks
Application Results
Applicants receive results no later than 6 weeks after the application deadline of their batch.
ResultsNotification
T+7/8 weeks
Project & Stipend Starts
Project starts, 3 month total project duration.
MentoringProject

2025 Project List

Explore and apply for projects in ESoC 2025! Note project specific application deadlines.

Machine Learning

Platform

AI-on-Demand and OpenML - The European AI Platform

Contribute to build the European AI-on-Demand Platform using OpenML - the open hubs for AI models, benchmarks, and projects. Funded by the Horizon Europe Programme of the EU.

Applied Project

Causal Learning

Electrolux - Causal Learning for Time Series

Build the open source AI landscape for causal AI in time series, with applications across supply chain management and retail! In collaboration with, and sponsored by Electrolux.

open source AI for drug discovery

Build open source AI for drug discovery, accelerating aptamer design for diagnostic and medical applications! Sponsored by German engineering services provider ecoSPECS.

Machine Learning

Causal Learning

pgmpy - The Causal Learning Library for Python

Contribute to pgmpy, the Python library for causal learning! Help implementing cutting edge causal learning algorithms, improve interopability, and enhance the user experience.

Machine Learning

Data Visualization

skore - Elevate ML Development with Built-in Recommended Practices

Contribute to skore, the scikit-learn sidekick! Help improve data visualization in skore by implementing more displays, a Plotly display backend and providing access to underlying display data.

pixi - Package Management Made Easy

Contribute to pixi, the universal package manager! Help improve user experience, build user interfaces, and extend scope to more programming languages!

rattler-build - Rust Crates for Mamba & Conda Packages

Contribute to rattler, fast mamba packager! Work on rattler-build to implement build process mechanisms, parallelize package installation, and improve the user experience.

Machine Learning

Optimization

Python

Gradient-Free-Optimizers & hyperactive - the python toolboxes for optimization

Contribute to Gradient-Free-Optimizers & hyperactive! Help improve the Python toolboxes for optimization and data collection. Projects include implementing new optimizers, improving documentation, and more!

ecoSPECS - AI for biotechnological cleanroom design

Build AI for design and equipment qualification of cleanrooms for biotech and pharmacological applications! Work with German engineering services provider ecoSPECS to fundamentally accelerate qualification processes in drug development, production, and monitoring worldwide.

Machine Learning

Time Series

sktime - The unified framework for machine learning with time series

Contribute to sktime! sktime offers a unified API for forecasting, classification, detection, and other learning tasks. Exciting projects are available in the areas of deep learning, foundation models, probabilistic forecasting, and more.

Deep Learning

Time Series

pytorch-forecasting & dsip-ts

Deep learning for time series forecasting made easy with PyTorch. Projects are available, focusing on improving model interfaces, upgrading the package to include foundation models, and more!