Checkly vs PartyKit: Which Is Better in 2026?

Checkly is a monitoring platform that uses code-based synthetic monitoring to continuously check that your APIs and critical user flows actually work in production — catching problems before your users do. Rather than just checking whether a server responds, Checkly runs real, scripted checks (including full browser-based end-to-end tests) against your application from around the world, verifying that key journeys — logging in, checking out, calling an API — behave correctly. This proactive, behavior-based monitoring gives teams confidence that their most important flows are working, not just that their servers are up.

The platform lets developers write checks as code, using familiar tools and frameworks, to monitor API endpoints and simulate real user interactions in a browser, running these checks on a schedule from multiple locations. When something breaks — an API returns errors, a checkout flow fails, performance degrades — Checkly alerts the team quickly, with the details needed to diagnose the issue. By embracing a "monitoring as code" approach that fits modern development workflows, and by testing real user-facing functionality, Checkly bridges the gap between testing and production monitoring in a way developers appreciate.

Checkly is used by development and DevOps teams that want to ensure their APIs and key user flows are reliable in production and prefer a code-based, developer-friendly approach to monitoring. By catching failures in critical journeys early — from anywhere in the world — it helps teams maintain reliability, protect the user experience, and resolve issues before they cause significant impact. Its synthetic, end-to-end focus complements traditional observability by verifying that things actually work as users would experience them. As applications grow more complex and reliability becomes ever more important, proactive synthetic monitoring of real flows is increasingly valuable. For development teams that want to monitor their APIs and critical user journeys in production with code-based synthetic checks, Checkly offers a powerful, modern and developer-friendly solution.

PartyKit is an open-source platform that makes building real-time, multiplayer and collaborative applications dramatically simpler. Real-time features — where multiple users see live updates, presence, cursors, chat or shared state — are increasingly expected in modern apps, but implementing the underlying infrastructure (persistent connections, state synchronization, scaling across many concurrent users) is genuinely hard. PartyKit abstracts this complexity, letting developers add real-time, multiplayer capabilities to their projects with a clean programming model and minimal boilerplate.

The platform is built on edge computing, running your real-time logic close to users for low latency, and provides a simple way to manage rooms of connected clients and their shared state. Developers write small server-side pieces ("parties") that handle the real-time coordination, and PartyKit takes care of the connections, scaling and infrastructure. This makes it possible to build things like collaborative editors, multiplayer games, live chat, real-time dashboards, shared whiteboards, and presence features without becoming an expert in distributed real-time systems or operating WebSocket infrastructure at scale.

Because it's open source and developer-focused, PartyKit fits naturally into modern web development workflows and integrates with frameworks and tools developers already use, making it approachable for adding a real-time layer to existing applications. It's popular with developers building interactive, collaborative experiences who want the power of real-time multiplayer without the heavy lifting. As users come to expect the live, collaborative feel popularized by tools like Figma and multiplayer apps, accessible infrastructure for building such experiences becomes increasingly valuable. PartyKit lowers the barrier so that real-time and multiplayer features are within reach for many more developers and projects. For anyone who wants to build collaborative, real-time, multiplayer applications on the edge — without wrestling with the underlying complexity — PartyKit offers an elegant, open and genuinely empowering platform.