Join the Hacktoberfest Open-Source AI Challenge: Ghost in the Machine! $2,850 in Prizes Across 21 Winners. - DEV Community

Posted on Oct 26 • Edited on Nov 13 • AI-assisted
Digital ofrendas and dead code séances won
Week 4 of our 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. 🎃🌼
This year's Hacktoberfest is all about building brand-new projects with open-source AI and open-weight models. Here's everything you need to know about Hacktoberfest 2026.
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.
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:
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.
Ghost in the Machine Submission Template
Alongside our overall winner, we have 20 prize categories for projects that use a specific partner's technology. You don't need to use any of these to win the overall prize, but if you've been curious about any of this tech, this is a great excuse to give one a try. Full descriptions are on the hub.
Featured categories:
Pro Tip: Partner category winners come from a smaller pool of submissions, so your odds are meaningfully higher.
Note: One project can enter every category it genuinely uses, but you can only win once per challenge, and we'll aim to celebrate as many different builders as possible across the month.
Free credits: several partners are giving participants credits and promo codes. Claim yours at hacktoberfest.com/my.
A huge thank you to our partners for making these prizes possible!
This is DEV, so your write-up matters most.
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.
All participants with a valid submission will receive a completion badge.
Publish a post on DEV using the submission template above. Tell us what you built and how you interpreted the theme, show us a demo, and explain why open innovation matters for what you built. If you can show us the moment your project landed, whether it gave someone chills or brought back a memory, even better!
Please review our judging criteria, rules, guidelines, and FAQ page before submitting so you understand our participation guidelines and official contest rules, such as eligibility requirements.
This is the last challenge of our Hacktoberfest series, and we've loved seeing everything you've built with open-source AI this month. Thank you to every participant, partner, and community member who showed up week after week. Let's make this final week one to remember!
Questions about the challenge? Drop them in the comments below.
Happy Hacktoberfest, and good luck! 👻🌼
A haunted terminal that digs through git history and tells you why a suspicious line exists would be fun. Especially when the ghost turns out to be your own commit from three years ago. Bonus points if it cites the commit before accusing you 😂
I tried to brought back, Ghost of BASIC language, which was one of the first programming language I learned.
More Details - tusharv.github.io/GBASIC/ Code at - github.com/tusharv/GBASIC Dev Post - dev.to/tusharv/ghost-basic-the-dea...
Thank you everyone. I am glad you like it.
More Context - I have build 4 projects but this is the first likes or interactions. dev.to/tusharv/hacktoberfest-2026-...
Just published my Week 4 submission: GitSéance — An Offline Digital Ofrenda Where Local Gemma Summons Deleted Code (And Refuses to Guess Why It Died)! 🌼🕯️💀
git blame only speaks for the living, so I built an offline git archaeologist powered by local Gemma 2 2B (temperature=0.25) that mines deleted functions from git log -p, places them on a marigold altar with Web Audio chimes, and uses a deterministic pre-flight guardrail + Sentry Agent Tracing so the model never fabricates fake stories when a commit message just says "wip cleanup".
Bonus Easter Egg for anyone who loves source code tricks: if you run python3 git_seance.py --mictlan or type mictlan on the live web altar, the code inspects its own AST in memory (#000dead) and decodes a hidden hex relic!
🔗 Read the write-up & try the Quine: dev.to/fgrandon/gitseance-an-offli...
Would love feedback from anyone else testing compact local models on messy git history! Happy Halloween & Día de los Muertos! 🎃🌼
Hey everyone! Just published my submission for Week 4: GitNecromancer (💀🔮).
It's a small tool and gothic web dashboard that scans your repo for abandoned branches, lets local Gemma 2 2B hold a 'séance' where the dead code speaks in the first person to explain why