AppSignal vs Keymetrics

AppSignal is a cloud application-monitoring service for developers, with error tracking, performance monitoring, logs, and tracing. Error tracking groups exceptions with backtraces and the deployment linked to each issue. Performance monitoring covers response times, throughput, slow endpoints, and slow queries. Log management provides full-text search, attribute filters, saved queries, live tail, and pattern-based alerts. Distributed tracing, transaction tracing, and log correlation are available. AppSignal lists support for Ruby, Elixir, Node.js, JavaScript, Python, Go, Java, PHP, and Rust, with integrations including Slack, GitHub, Jira, Linear, GitLab, and PagerDuty. Its MCP server lets AI assistants such as Claude, Cursor, and Zed query production errors, traces, and deploys. The free plan costs nothing and includes 30K requests, 1GB logging, five-day retention, and unlimited users, teams, applications, and dashboards. Paid access is $279 a year, billed yearly at $23.25/month, with 250K requests per month. A 30-day full-featured trial requires no credit card. AppSignal says it does not charge overages or stop monitoring when limits are crossed.

Keymetrics develops Node.js monitoring software around the open-source PM2 process manager. PM2 Plus provides a real-time web interface for production monitoring, including issue and exception tracking, deployment reporting, real-time logs, custom metrics, custom actions, and notifications through email, Slack, or webhooks. Applications and databases can be viewed together in real time or historically, with an aggregate view across applications. Its issue dashboard can identify when an error occurred, affected servers, the stack trace, the relevant code line, and logs from before the error. The @pm2/io library lets Node.js applications expose values, counters, meters, and histograms. PM2 Enterprise targets high-scale or critical Node.js services, adding customizable dashboards, threshold alerts, stored logs, and production CPU and memory profiling. Enterprise can run as an on-premise installation or as a dedicated or managed instance. Runtime is free; Plus is listed at $79 a month, and Enterprise pricing requires contact. Keymetrics supports API, Linux, self-hosted, and web deployments.