ReasonBlocks
ReasonBlocks is a YC Spring 2026 (P26) company. Based in San Francisco, CA, USA. Team of 2.
About ReasonBlocks
Summary
ReasonBlocks builds a runtime layer for AI agents that cuts token usage and raises task accuracy during execution, with improvements that compound across runs. It targets B2B teams running agentic AI workloads, replacing ad-hoc prompt engineering and post-hoc debugging with in-flight reasoning correction and token compression.
Go-to-market
B2B teams building or deploying AI agents are the buyers; the product operates as an infrastructure layer that integrates into existing agent pipelines.
From the Y Combinator listing
The runtime layer that makes AI agents cheaper and more reliable
ReasonBlocks is the runtime layer that makes AI agents cheaper and more reliable. We correct agent reasoning and compress tokens mid-run, with gains compounding across runs. On SWE-Bench pro we have seen a 52% token reduction and 42% accuracy lift.
Facts
- B2B / B2B
- San Francisco, CA, USA
- 2
- Active
- Early
Founders (2)
- Rohan Vij
- Sajeev Magesh
Score every batch against your own thesis
GPAgent's sourcing agent reads every company in a batch, scores each one against your fund's thesis in a private workspace, and lines up the founders worth meeting before Demo Day. You decide who to contact. Your scores, notes, and pipeline never appear on these pages.
How Accelerator intelligence works