Hacktoberfest Open-Source AI Challenge: Week 4
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Challenge 5 of 5 in our Hacktoberfest DEV Challenges. One prompt, a new theme every week.
Challenge Status:
Live
This year's Hacktoberfest is not about open source pull requests. There's no PR count to hit and no repos to hunt for. Instead, you build a brand-new project with open-source AI at its core, and write about it on DEV. Here's everything you need to know about Hacktoberfest 2026.
Week 4 of our five Hacktoberfest DEV Challenges starts today, and it's our final challenge of the series! Running through October 31, the Hacktoberfest Open-Source AI Challenge: Week 4 gives you the week to build, wrapping up on Halloween night just as Día de los Muertos begins.
Missed Week 3: Slow and Steady? No problem. Every challenge is a fresh start, so you're competing on the same footing as everyone else.
This week, we'll select one overall winner and a winner in each of our 20 partner categories. See all the challenges and current partner categories on the HF26 DEV Challenge Hub.
Free partner credits
Several partners are giving participants credits and promo codes, including Tinker, Render, Backboard, and a free .tech domain. Claim yours at hacktoberfest.com/my/promos.
Tinker by Thinking Machines
Render
Backboard
.tech Domains
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Key Dates
Contest start: October 26, 2026
Submissions due: October 31, 2026
Winners announced: Week of November 2
Badge Rewards
Hacktoberfest Challenge Completion Badge
Hacktoberfest Challenge Completion Badge
Hacktoberfest Challenge Winner Badge
Hacktoberfest Challenge Winner Badge
Find Out More
Ask questions and share your ideas on the Hacktoberfest Open-Source AI Challenge: Week 4 Launch Post.
View Launch Post
Challenge Prompt
Ghost in the Machine
Build something with open-source AI at its core.
That can mean running an open-weight model, building on an open-source agent harness or framework, running inference locally, or all three. Whatever you pick, the open pieces should be what makes your project work.
In your post, tell us why open innovation matters for what you built. Does it run on a laptop with no internet? Keep someone's data off a server they don't control? Let you fine-tune, swap models, or change how your agent behaves? Cost nothing to run? Tell us where your open-based approach worked better than a closed one.
This Week's Theme: Ghost in the Machine
Build something spooky, or something that honors the past in the spirit of Día de los Muertos, with open-weight models or open-source AI.
This week brings us Halloween on October 31 and Día de los Muertos on November 1 and 2, a stretch of the calendar when the line between past and present feels a little thinner. Whether that brings to mind things that go bump in the night, ofrendas glowing with candlelight and marigolds, or the memories and stories we carry with us, we want to see what it inspires you to build. The theme is intentionally broad, so interpret it however you'd like!
That can mean running an open-weight model, building on an open-source agent harness or framework, running inference locally, or all three. Whatever you pick, the open pieces should be what makes your project work.
A few ideas to get you going:
A haunted terminal that "possesses" your shell and whispers back eerie commentary on the commands you run
A virtual ofrenda builder that helps you write a remembrance for a loved one and gather their favorite foods, songs, and stories
An offline séance chatbot that channels the spirit of a long-dead programming language
A local oral history tool that records and transcribes family stories so they're never lost
A ghost story generator that weaves your smart home's sensor logs into a creepy tale of what happened while you were asleep
A project that brings an abandoned open-source tool or a forgotten corner of internet history back to life
In your post, tell us why open innovation matters for what you built. Does running your own model mean your project works with the lights (and the internet) off? Keep your family's photos and stories private and on your own machine? Make sure what you build isn't locked inside a service that might disappear someday? Tell us where your open-based approach worked better than a closed one.
Submission Template
Show your work. We'd love to see how you built it. Save your agent session with DevRelay and embed it in your post, or link to it. It's optional, but it helps the judges understand your process.
Judging Criteria
Writing Quality (weighted most heavily)
Relevance to the Prompt and Theme
Creativity
Technical Execution
Use of Partner Technology (optional)
Top Prize
$250 USD
- DEV++ Membership
- Exclusive winner badge Prize Categories Featured categories $200 for each winner
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