Spider-Lens

Spider-Lens analyzes Apache and Nginx logs and crawls sitemap-linked pages. It is best for site operators who want crawler, traffic, and technical page data in a free self-hosted tool. Its broad feature set has clear appeal, though setup depends on deployment choice and Nova requires a Gemini API key.

Overview

Spider-Lens brings log monitoring and site crawling into one application. Its dashboard covers requests, human visits, bots, errors, HTTP status trends, bot distribution, and 12-week patterns. The sitemap crawler adds page-level context, including titles, headings, word counts, canonical URLs, robots directives, and crawl depth. That pairing helps operators consider crawler behavior alongside the pages their site exposes.

The free self-hosted model avoids a stated subscription price or usage cap. It also means operators need access to server logs and must manage deployment. The native WordPress plugin avoids requiring Node.js on the server, while the standalone application requires Node.js 18 or later and npm 9 or later.

Key features

Log and crawler monitoring

The dashboard places traffic, bot activity, and HTTP health in one view. Spider-Lens detects 16 or more bots and visualizes crawler volume and crawl budget; crawler segmentation gives operators another way to examine that activity. This makes the tool useful when bot traffic and errors need to be understood alongside overall requests, though the dashboard's value depends on having the relevant logs accessible.

Performance and site crawling

Per-URL Time to First Byte reporting, configurable slow thresholds, and CSV and Excel exports give teams a way to identify slow responses and carry results into other workflows. The sitemap crawler follows internal links and extracts practical SEO and structure signals. Together, these features make Spider-Lens broader than a log dashboard, particularly for teams that want to relate server behavior to crawlable site content.

Alerts and integrations

SMTP email alerts and webhooks can flag 404 spikes, server errors, missing Googlebot, and weekly reports. Documented Discord and Slack webhooks and an MCP server for Claude Code or other compatible clients extend those notifications and data into existing workflows. These are useful operational hooks, although the project expects the operator to configure them.

Nova and data handling

Nova uses Google Gemini and requires a Gemini API key. Without one, the rest of the application continues to work, while Nova and AI Analysis show a configuration prompt. The README says Nova sends Google a compact JSON summary of about 500 tokens per request rather than raw logs. That distinction may matter to teams evaluating AI use with operational data, but the assistant remains optional and depends on an external API key.

Pricing

The Open-source self-hosted plan costs nothing. It includes the application with no paid plans or usage limits stated, so it suits users prepared to run and maintain their own deployment. There is no cheaper tier to compare; the trade-off is taking responsibility for setup and log access. Nova also requires a Gemini API key, which is separate from the application's free plan.

Platforms

Spider-Lens supports Linux, macOS, Windows, web, and self-hosted use. Deployment is available as a standalone Node.js application or a native WordPress plugin. The standalone version requires Node.js 18 or later, npm 9 or later, and access to Apache or Nginx logs; the WordPress plugin does not require Node.js on the server. Its interface supports 16 languages and can detect the browser language automatically.

Who it's for

Spider-Lens fits site owners and technical SEO teams who can access Apache or Nginx logs and want log analysis, crawler monitoring, page crawling, and alerts in one free deployment. WordPress operators who want to avoid a Node.js server dependency have a native plugin option. It is a weaker fit for users who want a managed service or who cannot take on deployment and log access; the standalone route also has explicit runtime requirements.

Pros and cons

• Pro: Log dashboards and sitemap crawling sit in one tool, connecting traffic and crawler signals with page-level SEO data.
• Pro: Alerts cover specific operational conditions, including 404 spikes, server errors, and missing Googlebot.
• Pro: The free self-hosted plan states no usage limits, and the WordPress plugin does not require Node.js on the server.
• Con: The standalone app requires Node.js 18 or later, npm 9 or later, and access to server logs, which adds deployment work.
• Con: Nova and AI Analysis require a Gemini API key, so the AI assistant is not included as a ready-to-use feature of the free deployment.
• Con: JWT authentication uses a seven-day token, and the maker advises changing the default JWT secret and admin password before deployment.

Alternatives

Choose SEO Log Auditor if you want a free, open-source MIT-licensed tool that runs locally. Choose Screaming Frog SEO Log File Analyser if its free tier's 1,000 log event lines and one project suit your needs, or if you want a paid licence at $139 a year.

CrawlGenius Log Analyzer is another freemium alternative. Log File Bot Traffic Cost Analyzer offers a free option organized around browser, CLI, and BigQuery log-size ranges. LogLens is a freemium alternative with a free tier described by a monthly request quota, website count, and history window. SEOMER has a limited-use free plan and paid token top-ups. AuditLabs SEO Log File Analyzer is a web alternative with a paid Supporter tier. Choose Crawl Lab if you want a free web tool with no sign-up, paid tier, or server-side size limit.

For more options, browse SEO Log File Analysis Tools.

Verdict

Spider-Lens is a strong choice for operators who can self-host and want log dashboards, crawler analysis, sitemap crawling, and alerts without a stated usage cap. Its main advantage is the range of those tools in one free application; its main drawback is the deployment responsibility, with Nova adding a separate Gemini API key requirement. Choose it when log access and self-management are acceptable, and look elsewhere if you need a managed setup.