Stealth Startup Spy #215 - Y Combinator W25
An early look at the Y Combinator Winter 2025 batch weeks before demo day! Full list available for download.
We are giving you early access to the Y Combinator Winter 2025 batch.
Every time a YC founder leaves any clues (publicly or privately) that they have joined an upcoming batch, we get an instant alert via Slack, and our system logs it.
Here are some of the trends from the upcoming Y Combinator Winter 2025 batch.
1. Agent-Driven Automation
Caseflood – Replaces law firm admin with AI agents
careCycle – AI voice teams for Medicare and ACA distributors
Calltree AI – Analyzes call center workflows to cut costs
Tally – AI agents automate accounting, tax, and audit
Bluebook – AI accounting agents to serve more clients
Toothy AI – Automates back-office operations for dental clinics
Agentin AI – Agents that move data and take actions across enterprise systems
2. AI Infrastructure & Data
Asteroid – Runtime supervision for AI agents (guardrails + human oversight)
Confident AI – LLM evaluation, benchmarking, and red-teaming
TrainLoop – Improves reasoning models with minimal developer effort
Augento – Fine-tuning as a service for struggling AI agents
Exla – Aggressive model quantization to reduce memory usage
Mastra – All-in-one AI dev toolkit (workflows, RAG, evals)
Gulp – Simplified real-time data pipelines for fraud, recommendations, etc.
AfterQuery – High-quality expert datasets for fine-tuning and RLHF
3. Generative AI Across Voice/Video
Leaping AI – Voice AI agents that handle up to 70% of calls end-to-end
Pickle – Lifelike AI clones for video calls, lip-sync in real time
Pinch – Real-time audio translation with synced lip movements
Mosaic – Natural-language-driven video editing
Dollyglot – Studio-quality voice cloning in any language
Riviera – AI voice agents for hotel front desks and reservations
Opine – Social media app to create custom AI video characters
4. Vertical AI in Regulated Markets
Archon – Cuts FedRAMP compliance from 16 months to 6
Candor – Auto-drafts proposals for defense, energy, biotech funding
Maive – Automates aerospace compliance paperwork on the shop floor
Harbera – AI for continuous physician credentialing
HealthKey – Matches patient EHR data with clinical trial eligibility
Vantel – AI software platform for commercial insurance brokers
Rada – Automates insurance calls for healthcare providers
5. Deep Tech & Robotics
Red Barn Robotics – Autonomous weed removal to boost crop yields
Pave Robotics – Robots that seal cracks in asphalt 24/7
Revise Robotics – Automating electronics refurbishment and resale
Maritime Fusion – High-temperature superconducting fusion reactors for marine use
Inversion Semiconductor – Next-gen chip fabrication machine, 15× faster
Orbital Operations – High-thrust, refuelable orbital vehicles
Splash – Autonomous surface vessels for national security
6. Biotech & Medical
Exin Therapeutics – Precision genetic therapy for neurological disorders
Uncommon Therapeutics – Multi-therapeutic platform tackling high-value diseases
Amby Health – AI-powered EMS workflow automation
Mecha Health – Transparent, AI-driven radiology reporting
Cenote – AI automates medical practice back-office tasks
Vetnio – Reduces vet admin work by 40% with AI
7. Productivity & No-Code
a0.dev – Generates custom React Native apps in days
Woz – AI platform to build and grow software businesses (no coding required)
Onlook – Open-source Cursor for Designers; edit live websites instantly
Nitrode – AI-assisted game creation and launch
Promptless – Automatically updates your public documentation
Quantstruct – AI-generated changelogs and implementation guides
Sammy Labs – AI that explores your app like a real user (QA automation)
8. Classic B2B SaaS + AI
Stamp – AI-powered email client for automated sorting and replies
Ergo – CRM that auto-updates from calls and emails
Overstand – Summaries of customer communications for busy execs
Spott – Next-gen ATS & CRM for recruitment agencies
Sammy – AI-based QA automation for apps
Mercura – AI-assisted quoting from BOMs and spec sheets
Solidroad – QA and coaching for live call center reps
Opine – Social media for AI avatars and voice-enabled creations
FYI - This dataset is a 3-sheet report with full founder profiles and emails, company details and this full market map. (Limit is 50 downloads)
Here’s some of the stealth activity from this batch (full list available here)
🔮YCW25 Startups Spotted Early
We love tracking early-stage startups before they hit the spotlight, and this YC batch proves it: several companies we featured months ago just made it into Y Combinator.
HealthKey
🕒 Featured 17 months before YC
Helping doctor’s offices generate revenue by using AI to match patients with clinical trials. Their platform automates patient prescreening, unlocking new revenue streams from Big Pharma.
Team: Josh Sabol
Leaping AI
🕒 Featured 12 months before YC
Powering voice AI agents that automate complex, high-volume contact center operations. Their human-like voice AI agents automate up to 70% of customer support calls—all while maintaining a 90% customer satisfaction rate.
Team: Shraey Bhatia, Arkadiy Telegin, Kevin Wu
Overstand
🕒 Featured 6 months before YC
A customer insights platform that transforms Slack, emails, WhatsApp, and call transcripts into actionable insights—helping founders stay connected, spot trends, and drive impact.
Team: Derrick Cheng, Mihir Patil, Senta Knuth
General Trajectory
🕒 Featured 3 months before YC
Training vision-language-action (VLA) models to bring AI to the physical world, automating tasks like palletization, sorting, picking, and packing.
Team: Joshua Belofsky, Jack Armstrong
Y Combinator’s Winter 2025 Batch has their Demo Day on March 12th, 2025 so this is your early look at all of the startups participating in this event.
Most of these founders and companies are not yet listed in the YC directory and we will constantly update the dataset as founders continue to exit stealth.
Notice: This link will be taken down at 50 downloads and before 11:59pm EST on Friday of next week....
Stay Stealthy,
Drake
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Stealth Startup Spy is a data-driven newsletter for investors, journalists and tech enthusiasts interested in uncovering the next big move for key talent, real-time stealth company launches and technology advancements not in plain sight. We leverage the technology built at Gravity to shine a light on the hidden world of stealth startups.
Love this early look at the YC W25 batch! Some really exciting trends here agent-driven automation and AI infrastructure are clearly dominating. Leaping AI and Overstand seem particularly promising. Curious to see which of these will break out post-Demo Day. Anyone else have favorites?