Rystic
Rystic provides locally runnable, stateful simulators for third-party APIs like Slack, GitHub, and Stripe, allowing developers to test integrations without rate limits or network dependencies. Each simulator is continuously verified against the live API before release, with fidelity percentages published per commit. The platform supports local execution on laptops or CI runners, with enterprise options for fully offline deployments.
- Developer Tools
- Software Only
Funding
Raised to date
$500KRaised to date based on public sources. This may differ from the amount the company actually raised and is based only on what is publicly available on the internet.
Founders
Founder details are not available yet.
Product
Problem
Developers building integrations with third-party APIs often face rate limits, network dependencies, and inconsistent test environments when using live services. This slows development, makes testing unreliable, and complicates CI/CD pipelines.
Solution
Rystic provides stateful simulators for software services like Slack, GitHub, Kalshi, and Stripe, enabling developers to run these APIs locally on their laptop or CI runner without rate limits. The simulators maintain state across calls, so operations like adding a customer and listing customers behave consistently. Before every release, the same requests are sent to both the live API and the simulator to verify behavioral agreement, with the measured fidelity percentage published from CI per commit. Enterprise deployments can run fully offline with a licensed build.
Target Audience
Primary users are software developers and engineering teams building integrations with third-party APIs, as well as enterprises running RL environments and agent evals at scale.
Features
- Stateful simulation: every call sees the ones before it, preserving data across operations like create, list, and delete
- Verified fidelity: the same requests are run against live APIs and simulators before each release, with agreement percentages published per commit
- Local execution: runs on a laptop or CI runner with no rate limits
- Offline capability: Enterprise builds run fully offline with a license file
- Fault injection: Pro and Enterprise plans support latency and fault injection (429, 503) for testing error handling
- Settable state: users can configure the simulator's state to test specific scenarios
- Verified UIs: Pro and Enterprise plans include verified user interfaces for premium simulators