Come join us for Haunted Hacks to kick off Halloween this year. Hosted by Terse (F26) and AgentRelay (F26), brought to you by OpenAI, Mastra (W25) and Supabase (S20).

OpenAI is offering $100 in OpenAI API credits per participant.

Love Durable Objects? Come build with our Open Source alternative!

Tired of copy/pasting messages between your agents? Come see how much you can build when you let agents collaborate directly with Agent Relay!

Want to do both at the same time? Even better!

Lunch, snacks, candy, bad Halloween/AI puns, swag, coffee, and prizes are all included.

Tracks include:

  • Hackathon winner: A guaranteed YC interview

  • Stateful Apps: Build with durable-actors from Terse - iPhone Duo

  • Agent to agent communication built with Agent Relay: Mac Mini

  • Costume contest: Bragging rights

October 31, 2026 · YC Office · San Francisco, CA Eligibility

We recommend working in groups, and we're happy to help you form a team if you're coming on your own.

This is an in-person event in San Francisco. You must be able to attend on-site to participate.

Attendees must be 16 or older.

Schedule

  • 10:00am - 11:00am: Doors Open + Registration

  • 11:00am: Hacking begins

  • 1:00pm: Lunch

  • 4:00pm: Submission deadline

  • 4:00pm - 5:00pm: Judging

  • 5:00pm - 6:00pm: Award Ceremony


What to build

The Actor world is hot right now. Come build your own Software Factory, long-running agent, multiplayer AI system or something super creative you've been itching to try out.

Projects should ideally use either Durable actors, or Agent Relay (bonus points if you use both at the same time).\


Rules

All code must be created at the hackathon.

Thinking of ideas before the hackathon is fine.

Judging


We will be using devpost! We recommend setting up your account ahead of time.

The top entries will demo live at the end of the event, and judges will select winners from those demos.

Judges are looking for either very well-executed products or incredibly creative use cases using Durable Actors and Agent Relay. Again, bonus points if you can do both!

Judges will be announced soon.

Prizes

 

The best overall project will receive a guaranteed YC Interview, $5k in OpenAI API credits and 3 months free of Mastra Platform.

The second place team will receive $2.5k in OpenAI API Credits and 2 months free of Mastra Platform.

The third place team will receive $1k in OpenAI API Credits and 1 month free of Mastra Platform.


The best project using Durable Actors will get an iPhone duo. 

The best project built using Agent Relay will get a Mac mini.

The project deemed the “most likely to scale to millions” will receive $1K in credits from Supabase 


More prizes will be announced!

Don’t Know What Actors/Durable Objects Are?

Here are some great resources:
- https://boristane.com/blog/what-are-cloudflare-durable-objects/

 

- https://x.com/aboodman/status/2088155104851657110

 

Requirements

What to build

Build a project that uses AI in real time. Projects must be started on October 31, 2026. Teams must have 2–4 members; solo entries are not allowed. Only confirmed in-person attendees may submit projects.

What to submit

Complete your final submission on Devpost by 4:00pm Pacific Time on October 31, 2026. Entries left as drafts or not submitted by the deadline will not be considered by the judges.

A valid submission must include:

  1. Project name
  2. A link to a video demonstrating your project
  3. Technologies used to build your project
  4. APIs and capabilities used
  5. A description of your project
  6. At least one screenshot

Writeup

Your Devpost writeup is your entry and will be judged. Explain what you built, how it works, and what makes its use of real-time AI distinctive. A project title is required. You may also include a subtitle, thumbnail, and card images.

Submission tracks

All submissions will be considered for the overall hackathon prize.

  • Stateful Apps track: Projects built with durable-actors from Terse qualify for consideration for the iPhone Duo prize.
  • Agent-to-agent communication track: Projects built with Agent Relay for agent-to-agent communication qualify for consideration for the Mac Mini prize.

Assets

Include at least one screenshot and a link to a video demonstrating your project. You may include additional supporting assets.

Project description

Describe what your project is, what it does, and how it uses AI in real time. Explain the technologies, APIs, and capabilities you used. For a technology track, describe how your project uses that track’s technology.

Attendance registration happens exclusively through the YC event page. Devpost is only for project submissions.

Hackathon Sponsors

Prizes

3 non-cash prizes
YC Interview
1 winner

A guaranteed interview with YC

iPhone Duo
1 winner

An iPhone Duo

Mac Mini
1 winner

A Mac Mini

Devpost Achievements

Submitting to this hackathon could earn you:

Judges

Olivier Simard-Morissette

Olivier Simard-Morissette
Terse AI

Judging Criteria

  • Use of Real-Time AI and Track Technology
    How meaningfully does the project use AI in real time? For the Terse and Agent Relay track prizes, how effectively does it use the corresponding technology?
  • Originality and Creativity
    How fresh and inventive is the idea? Does it demonstrate an unexpected or creative use of real-time AI?
  • Execution and Demo
    How well does the project work? Consider functionality, polish, and how clearly and convincingly the demo communicates the concept.
  • User Experience and Design
    Is the experience intuitive, cohesive, and thoughtfully designed? Does the design support the project’s intended use?
  • Potential and Impact
    Does the project address a meaningful problem or demonstrate a compelling use case? Could the idea be developed further into something useful?

Questions? Email the hackathon manager

Invite others to compete

Hackathon sponsors

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.