Highlight.io

Highlight.io is an open-source, full-stack monitoring platform that combines session replay, error monitoring, logging, and distributed tracing into a single unified tool. Founded in 2021 and backed by Y Combinator (W23 batch), Highlight.io was built to address a common frustration among development teams: the need to juggle multiple disconnected monitoring tools to understand what is happening in their applications. By bringing session replay, error tracking, logs, and traces together in one platform, Highlight.io allows developers to quickly connect user-facing issues with their underlying technical causes.

The platform is fully open source under the Apache 2.0 license, with the complete codebase available on GitHub. This open-source foundation is one of Highlight.io's most significant differentiators, giving organizations the option to self-host the entire platform on their own infrastructure. For European companies with strict data residency requirements, self-hosting means complete control over where monitoring data is stored and processed, which can be essential for GDPR compliance and data sovereignty. In 2025, the Highlight team was acquired by LaunchDarkly, the feature management platform, which has expanded the product's capabilities and enterprise reach.

Session Replay

Session replay is arguably Highlight.io's flagship feature and the capability that drew initial attention to the platform. It records user interactions with your web application -- clicks, scrolls, navigation, form inputs, network requests, console logs, and DOM mutations -- and plays them back as a video-like replay. This allows developers and support teams to see exactly what a user was experiencing when they encountered a problem, eliminating the guesswork that typically accompanies bug reports.

What makes Highlight.io's session replay particularly valuable is how deeply it integrates with the error monitoring and logging features. When an error occurs during a user session, you can click directly from the error to the exact moment in the session replay where it happened. You can see the user's screen, the network requests that were in flight, the console output, and the full error stack trace all in one unified view. This contextual linking between session replay and error data dramatically reduces the time it takes to understand and reproduce bugs.

Error Monitoring

Highlight.io's error monitoring captures both frontend and backend errors with full context. On the frontend, it automatically captures unhandled exceptions, promise rejections, and console errors along with session replay context. On the backend, SDKs are available for popular frameworks including Node.js, Python, Go, Java, Ruby, and .NET, which capture exceptions with full stack traces, request context, and custom metadata. Errors are automatically grouped and deduplicated to reduce noise, and the platform provides trend analysis to help teams identify whether errors are increasing or decreasing over time.

The error monitoring integrates smoothly with popular alerting tools. You can configure alerts based on error frequency, set up Slack or email notifications, and connect with incident management platforms. For teams migrating from Sentry, Highlight.io covers the same core error tracking use cases while adding the session replay context that Sentry lacks in its basic offering. The ability to see the exact user session where an error occurred, rather than just a stack trace and metadata, is a genuine improvement in the debugging workflow.

Logging

Highlight.io includes a full logging pipeline that ingests, indexes, and searches application logs. Backend SDKs automatically correlate logs with traces and sessions, meaning you can follow a user's journey from the session replay through to the specific log lines generated by their requests on your backend. The logging interface supports structured log queries, faceted filtering, and log pattern analysis, providing capabilities similar to dedicated logging platforms like Datadog Logs or Elastic.

Log ingestion supports multiple formats and can receive data from various sources including application SDKs, the OpenTelemetry Collector, and standard log shipping tools. For teams that currently use separate tools for application monitoring and log management, Highlight.io's integrated logging can simplify the stack by consolidating these functions into a single platform. The log search and visualization capabilities are solid for most use cases, though teams with extremely high log volumes or complex analytical requirements may still benefit from dedicated logging infrastructure.

Distributed Tracing

Highlight.io supports distributed tracing using the OpenTelemetry standard, which has become the industry-standard framework for observability instrumentation. Traces capture the full journey of a request through your application's services, showing where time is spent and where bottlenecks occur. Because Highlight.io uses OpenTelemetry, organizations that have already instrumented their applications with OTel can send trace data to Highlight.io without changing their instrumentation code.

The tracing interface shows waterfall views of request spans, service maps, and latency distributions. Traces are correlated with sessions, errors, and logs, maintaining the unified observability philosophy that runs through the entire platform. For teams building microservices architectures, this trace correlation is particularly valuable because it connects frontend user experience problems with specific backend service performance issues across the distributed system.

Self-Hosting and Data Control

One of Highlight.io's most compelling features for European organizations is the ability to self-host the entire platform. The open-source codebase includes Docker deployment configurations and documentation for running Highlight.io on your own infrastructure. Self-hosting gives you complete control over data storage, processing, and retention, which is invaluable for organizations with strict data residency or sovereignty requirements under GDPR or industry-specific regulations.

The self-hosted deployment uses ClickHouse for data storage and is designed to scale horizontally. While self-hosting requires more operational overhead than using the managed cloud service, the trade-off is worth it for organizations that cannot send monitoring data to third-party infrastructure. Highlight.io's documentation for self-hosting is reasonably comprehensive, though teams should expect to invest some engineering time in setup, configuration, and ongoing maintenance.

Developer Experience and Integration

Getting started with Highlight.io is straightforward. For frontend monitoring, adding the JavaScript snippet to your application typically takes a few minutes and immediately begins capturing session replays and frontend errors. Backend SDKs are available for the most popular frameworks and languages, and the OpenTelemetry support means that existing OTel instrumentation works out of the box. The onboarding documentation includes framework-specific guides for Next.js, React, Vue, Angular, Express, Django, Flask, and many others.

The platform provides integrations with popular development tools including GitHub, GitLab, Linear, Jira, Slack, Discord, and PagerDuty. These integrations allow teams to create issues directly from errors, receive alerts in their preferred channels, and link monitoring data to their existing workflows. The API is well-documented for teams that want to build custom integrations or extract data programmatically.

Pricing and Plans

Highlight.io offers a generous free tier that includes session replay, error monitoring, logging, and tracing with reasonable usage limits. This makes it accessible for small teams and personal projects that want full-stack monitoring without upfront costs. The paid plans start at approximately $150 per month and scale based on usage, with pricing tied to the volume of sessions, errors, logs, and traces ingested. Enterprise plans add features like SSO, advanced access controls, dedicated support, and higher data retention periods.

Compared to competitors like Datadog, New Relic, or LogRocket, Highlight.io's pricing is competitive, particularly for small to mid-sized teams. The combination of session replay, error monitoring, logging, and tracing in a single platform with a single bill can represent significant cost savings compared to using separate tools for each function. For organizations that choose to self-host, the open-source version is free with no licensing costs, though infrastructure and operational costs still apply.

Highlight.io vs. LogRocket and Sentry

The most common comparisons for Highlight.io are with LogRocket (for session replay) and Sentry (for error monitoring). LogRocket is the established leader in session replay but is a proprietary, closed-source platform with higher price points. Sentry dominates the error monitoring space but has only recently added session replay features, and its replay capabilities are less mature. Highlight.io occupies a unique position by offering both session replay and error monitoring at parity, plus logging and tracing, all in an open-source package.

For European organizations, Highlight.io's self-hosting option is a decisive advantage. Neither LogRocket nor Sentry offer the ability to run the full platform on your own infrastructure with the same degree of openness. If data sovereignty is a requirement, Highlight.io's open-source, self-hostable architecture makes it the clear choice among full-stack monitoring platforms that include session replay capabilities.

Limitations and Considerations

Highlight.io is a younger platform compared to established monitoring giants like Datadog or New Relic, and this shows in some areas. The alerting and dashboarding capabilities, while functional, are not as sophisticated as dedicated monitoring platforms. High-volume deployments may require careful tuning of the self-hosted infrastructure, and the community around self-hosted deployments is still growing. The 2025 acquisition by LaunchDarkly introduces questions about the long-term direction of the open-source project, though the company has maintained its commitment to open source so far.

Final Verdict

Highlight.io stands out as a compelling monitoring solution that brings session replay, error monitoring, logging, and tracing into a single open-source platform. For European development teams seeking an alternative to closed-source US monitoring giants, the combination of full-stack observability, open-source transparency, and self-hosting capability makes it a strong choice. The free tier is generous enough for small teams to evaluate the platform thoroughly, and the paid plans are competitively priced for the breadth of functionality offered. While it may not match every feature of more established platforms, the unified approach to monitoring and the ability to keep all data on your own infrastructure make Highlight.io a platform worth serious consideration.