Highlight – Debug customer-facing issues with replay

In plain words

Highlight is a debugging tool that uses session replay to help development teams reproduce and understand customer-facing errors. It captures user interactions and context around issues, eliminating the need for manual screenshots or videos from users. The tool is designed for teams drowning in error reports and support tickets who want better visibility into actual user impact and UX problems without extensive manual investigation.

written from the facts on this page · September 2026

From the sources

LaunchDarkly helps teams safely manage code and AI agents in production with feature flags, progressive delivery, automated rollback, and runtime control.

The runtime control layer for AI development, de-risking releases, and enabling systems that heal and optimize themselves. Progressively release changes and roll back instantly based on real-time impact. Automatically keep agents on track, mitigating bad behavior and steering responses in real time. Test prompts and models in production and dynamically route traffic to the best option. Instantly remediate failing code and misbehaving agents (without human intervention). Experiment with code and agents in production and optimize based on real-world results. Ship confidently with automatic recovery and continuous improvement built in. See end-to-end examples of building on the LaunchDarkly…from highlight.io

In the maker’s words, at launch

Hey HN, I’m Jay, a co-founder at Highlight and a YC alum; excited to share our replay-based debugging tool! TLDR; if you're using a tool like Fullstory for debugging, or you have trouble understanding the actual impact of your errors (e.g. in sentry), you should give us a try! We built Highlight because we constantly…

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  Highlight2022 · launchdarkly.com · ▲285

  Understand and debug customer issues with confidence

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  Error Monitoring & Session Replay2023 · launchdarkly.com · ▲269

  Stop guessing why bugs happen

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  We’re open-sourcing our session replay tool2023 · github.com · ▲408

  Hey HN! We’re open-sourcing highlight.io (https://github.com/highlight/highlight), a session replay and error monitoring tool. Highlight.io gives you a high-precision video-like replay of what users are doing when an error or exception occurs in your web app, along with a full-fledged error monitoring experience (similar to bugsnag, rollbar, etc..). The main value prop of highlight.io is that we help you understand the full context surrounding an error and allow you to drill down to the code path that a user invoked (i.e user clicked button X, sent network request Y, and…

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  Highlight2021 · launchdarkly.com · ▲318

  See and act on your webapp's issues and interactions

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  Comments by Highlight2022 · ▲180

  Collaboration on Highlight makes debugging faster than ever

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  An open source performance monitoring tool2024 · github.com · ▲135

  Hey HN. We’re Jay and Vadim from Highlight.io (https://highlight.io). We’re building an open source [1] monitoring platform for web applications. Today we’re excited to be sharing a performance tool we’ve been working on, which helps you inspect the latency of code execution from the client to the server. As engineers at past startups, we often had to debug slow queries, poor load times, inconsistent errors, etc... While tools like Jaegar [2] helped us inspect server-side performance, we had no way to tie user events to the traces we were inspecting. In other words, although we had…

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