Synth

Synth builds software for applied AI teams to develop, evaluate and improve models and agents locally and in the cloud. Synth Workshop brings experiments, traces, scores and artifacts into a local workbench, supporting local models and provider APIs. Stack supplies a research engineering harness, while Managed Research runs tasks against repositories and returns reviewable artifacts and, when code changes result, pull requests. Teams can launch and inspect research through MCP, a Python SDK or a frontend, steering work through a shared message queue.

Founded in 2024, Synth is led by founder and CEO Josh Purtell, previously a research scientist at accounting automation company Basis. Its engineering work emphasizes inspectable experimentation: jesterky, an open Rust workflow system, records execution and replays orchestration against recorded outputs without promising identical future model responses. Research Factory extends Managed Research into repeated cycles with budgets and concurrency limits, exporting immutable candidates for evaluation on held-out inputs by an evaluator outside the worker’s workspace.

Synth participated in Y Combinator’s Fall 2024 batch. Its 2026 Managed Research offering combines a free plan with Standard at $20 per month and Max at $200 per month, using shared usage allowances and additional flex credits. Stack can run without a Synth account; hosted features and API access are optional.