# Sentinel

> Sentinel is a website and infrastructure monitoring platform for agencies and freelance developers. It monitors uptime, SSL certificates, DNS records, domain expiration, page keywords and JSON API responses from four global regions, with instant alerts and client-facing status pages.

## Product Pages

- [Features](https://sentinel.rootstuff.io/features): Every Sentinel monitoring capability in one place — uptime, SSL, DNS, keyword, API, ping, port, heartbeat and cron.
- [Pricing](https://sentinel.rootstuff.io/pricing): Simple, transparent monitoring plans. Start free, upgrade as you grow, 14-day free trial on paid plans.
- [Integrations](https://sentinel.rootstuff.io/integrations): Connect Sentinel to Slack, Discord, webhooks and the tools your team already uses.
- [Status Pages](https://sentinel.rootstuff.io/status-pages): Public and password-protected status pages that keep clients informed during incidents.
- [Desktop App](https://sentinel.rootstuff.io/desktop): A macOS menu bar app for at-a-glance monitor status without opening the dashboard.
- [MCP for AI Assistants](https://sentinel.rootstuff.io/mcp): Connect Claude, ChatGPT and any MCP-compatible AI assistant to your monitoring over the open Model Context Protocol. Ask “is anything down?” in plain language, triage incidents and pause monitors with 21 built-in tools.
- [Uptime Monitoring](https://sentinel.rootstuff.io/uptime-monitoring): 24/7 uptime checks every 30 seconds from four global regions with instant alerts.
- [SSL Certificate Monitoring](https://sentinel.rootstuff.io/ssl-certificate-monitoring): Track SSL certificate expiry and chain issues, with alerts weeks before a cert lapses.
- [DNS Monitoring](https://sentinel.rootstuff.io/dns-monitoring): Watch A, AAAA, MX and NS records and detect unauthorized or accidental DNS changes.
- [Keyword Monitoring](https://sentinel.rootstuff.io/keyword-monitoring): Verify expected text appears on a page — or detect defacement and error messages.
- [API Monitoring](https://sentinel.rootstuff.io/api-monitoring): Send custom HTTP requests and assert on the JSON response body to catch silent API failures behind a 200 OK.
- [Ping Monitoring](https://sentinel.rootstuff.io/ping-monitoring): ICMP echo from every region with multi-region consensus. For servers, network devices and anything that does not speak HTTP.
- [TCP Port Monitoring](https://sentinel.rootstuff.io/port-monitoring): TCP connection checks for databases, mail, SSH and any custom service listening on a port. Multi-region consensus, categorized failure reasons.
- [Heartbeat Monitoring](https://sentinel.rootstuff.io/heartbeat-monitoring): Push-based dead-man's-switch monitoring for cron jobs, backups and background workers. Your job pings a URL; a missing ping opens an incident.
- [Cron Job Monitoring](https://sentinel.rootstuff.io/cron-monitoring): Monitor scheduled cron jobs against their own cron expression and timezone. Get alerted the moment a scheduled run is missed or fails.
- [Domain Expiration Monitoring](https://sentinel.rootstuff.io/domain-expiration-monitoring): Never miss a domain renewal — get alerted well before a domain registration expires.
- [Response Time Monitoring](https://sentinel.rootstuff.io/response-time-monitoring): Track latency from multiple regions and spot performance regressions before users do.
- [Multi-Region Monitoring](https://sentinel.rootstuff.io/multi-region-monitoring): Check from four regions and require consensus to cut false alarms from regional blips.
- [Uptime Reports](https://sentinel.rootstuff.io/uptime-reports): Scheduled and on-demand uptime reports you can share with clients and stakeholders.
- [Incident Management](https://sentinel.rootstuff.io/incident-management): Automatic incident timelines, root-cause detail and resolution notes for every outage.
- [Website Monitoring for Agencies](https://sentinel.rootstuff.io/website-monitoring-for-agencies): Centralized monitoring for agencies managing dozens or hundreds of client websites.
- [WordPress Website Monitoring](https://sentinel.rootstuff.io/website-monitoring-for-wordpress): Monitoring built for WordPress sites — uptime, SSL, plugins-induced outages and more.
- [E-commerce Website Monitoring](https://sentinel.rootstuff.io/website-monitoring-for-ecommerce): Protect checkout, inventory and payment flows with monitoring tuned for online stores.
- [SaaS Website Monitoring](https://sentinel.rootstuff.io/website-monitoring-for-saas): Monitor SaaS apps and their health-check and API endpoints from four global regions.
- [Uptime Monitoring for Agencies](https://sentinel.rootstuff.io/uptime-monitoring-for-agencies): Uptime monitoring for digital agencies. Watch every client site from one dashboard, prove uptime with branded reports and status pages, and get alerted before clients notice.
- [Uptime Monitoring for Freelancers](https://sentinel.rootstuff.io/uptime-monitoring-for-freelancers): Affordable uptime monitoring for freelance developers and designers. Start free, get alerted before clients notice downtime, and look more professional.
- [Uptime Monitoring for SaaS](https://sentinel.rootstuff.io/uptime-monitoring-for-saas): Uptime monitoring for SaaS products. Track SLA targets, monitor API and health-check endpoints from four regions, alert on-call, and reduce churn with a public status page.
- [Sentinel vs StatusCake](https://sentinel.rootstuff.io/sentinel-vs-statuscake): How Sentinel compares to StatusCake for agency website monitoring — per-minute checks, bundled DNS/ping/port/heartbeat, branded status pages and automated client reports.
- [Sentinel vs UptimeRobot](https://sentinel.rootstuff.io/sentinel-vs-uptimerobot): How Sentinel compares to UptimeRobot — flat pricing with no SMS credit packs or per-seat fees, commercial-use free tier, and automated client reports.
- [Sentinel vs Pingdom](https://sentinel.rootstuff.io/sentinel-vs-pingdom): How Sentinel compares to Pingdom — simple flat tiers instead of usage-based pricing, a free-forever tier, and agency-focused status pages and reports.
- [Sentinel vs Better Stack](https://sentinel.rootstuff.io/sentinel-vs-betterstack): How Sentinel compares to Better Stack — monitoring built for agencies without on-call, log-management or per-responder pricing overhead.
- [Sentinel vs Uptime Kuma](https://sentinel.rootstuff.io/sentinel-vs-uptimekuma): A hosted alternative to Uptime Kuma — the real cost of self-hosting (time, maintenance, single-region, single point of failure) versus fully managed monitoring with multi-region checks, a REST API and MCP for AI assistants.

## AI Agents (MCP)

Sentinel is built to be operated by AI agents. It exposes an MCP (Model Context Protocol) server over Streamable HTTP at https://sentinel.rootstuff.io/mcp/sentinel with 21 tools: uptime summaries, monitor and incident CRUD, performance and DNS history, SSL certificate expiry, and on-demand global URL checks.

- Authenticate with an API token (Authorization: Bearer header), created at https://sentinel.rootstuff.io/user/api-tokens, or via OAuth 2.1 with dynamic client registration at https://sentinel.rootstuff.io/mcp/sentinel-oauth.
- API and MCP access requires a paid plan: read-only tools on Starter, full read/write on Pro and Business.
- Token permissions (read, create, update, delete) are enforced, so an autonomous agent can be given a read-only or otherwise scoped credential.
- [Connecting AI Assistants (MCP)](https://sentinel.rootstuff.io/docs/mcp): setup guide for Claude and other MCP clients
- [MCP Tools Reference](https://sentinel.rootstuff.io/docs/mcp-tools): every tool with its inputs and outputs
- [REST API reference](https://sentinel.rootstuff.io/docs/api-access): the same capabilities over plain HTTP

## Documentation

- [Introduction](https://sentinel.rootstuff.io/docs/introduction)
- [Quick Start](https://sentinel.rootstuff.io/docs/quick-start)
- [Website Monitoring](https://sentinel.rootstuff.io/docs/website-monitoring)
- [SSL Certificates](https://sentinel.rootstuff.io/docs/ssl-certificates)
- [DNS Monitoring](https://sentinel.rootstuff.io/docs/dns-monitoring)
- [Keyword Monitoring](https://sentinel.rootstuff.io/docs/keyword-monitoring)
- [API Monitoring](https://sentinel.rootstuff.io/docs/api-monitoring)
- [Ping Monitoring](https://sentinel.rootstuff.io/docs/ping-monitoring)
- [Port Monitoring](https://sentinel.rootstuff.io/docs/port-monitoring)
- [Heartbeat Monitoring](https://sentinel.rootstuff.io/docs/heartbeat-monitoring)
- [Cron Job Monitoring](https://sentinel.rootstuff.io/docs/cron-monitoring)
- [Notifications](https://sentinel.rootstuff.io/docs/notifications)
- [Status Pages](https://sentinel.rootstuff.io/docs/status-pages)
- [Uptime Reports](https://sentinel.rootstuff.io/docs/uptime-reports)
- [Team Management](https://sentinel.rootstuff.io/docs/team-management)
- [API Access](https://sentinel.rootstuff.io/docs/api-access)
- [CLI](https://sentinel.rootstuff.io/docs/cli)
- [Slack Integration](https://sentinel.rootstuff.io/docs/slack)
- [Discord Integration](https://sentinel.rootstuff.io/docs/discord)
- [Microsoft Teams Integration](https://sentinel.rootstuff.io/docs/teams)
- [Webhooks](https://sentinel.rootstuff.io/docs/webhooks)
- [Connecting AI Assistants (MCP)](https://sentinel.rootstuff.io/docs/mcp)
- [MCP Tools Reference](https://sentinel.rootstuff.io/docs/mcp-tools)
- [CI/CD & Pausing Monitors](https://sentinel.rootstuff.io/docs/cicd-pause-monitoring)
- [Import & Export](https://sentinel.rootstuff.io/docs/import-export)
- [Troubleshooting](https://sentinel.rootstuff.io/docs/troubleshooting)

## Blog

- [Sentinel Is Now in the Official MCP Registry](https://sentinel.rootstuff.io/blog/sentinel-official-mcp-registry): Sentinel is listed in the official MCP Registry as io.rootstuff/sentinel: a verified, first-party server that lets Claude, ChatGPT, and any MCP client operate your monitoring in plain language.
- [How to Tell If Your Website Has Been Hacked: 9 Warning Signs](https://sentinel.rootstuff.io/blog/how-to-tell-if-your-website-is-hacked): Most hacked websites don't look hacked. The nine warning signs of a compromised site, how to confirm it, what to do right now, and the external checks that catch the next one in minutes.
- [Website Defacement: How to Detect It in Minutes, Not Days](https://sentinel.rootstuff.io/blog/website-defacement-monitoring): What website defacement is (from full page takeovers to hidden spam and cloaked redirects), why detection speed decides the damage, and how to set up content checks that catch it fast.
- [What Happens When a Domain Expires (and How to Never Let It Happen)](https://sentinel.rootstuff.io/blog/what-happens-when-a-domain-expires): The domain expiration timeline stage by stage, why a dropped domain is a security incident and not just an outage, and the monitoring layer that catches silent auto-renew failures.
- [Open-Source Uptime Monitoring Tools (2026): Self-Hosted Options Compared](https://sentinel.rootstuff.io/blog/open-source-uptime-monitoring-tools): The best open-source uptime monitoring tools in 2026 — Uptime Kuma, Gatus and more — what they do well, and the honest cost of self-hosting before you commit.
- [Uptime Monitoring Tools With an API — and Now MCP for AI Assistants](https://sentinel.rootstuff.io/blog/uptime-monitoring-tools-with-api): Why an API changes what monitoring can do, what to look for, and the new layer: MCP, which lets AI assistants like Claude and ChatGPT query your monitoring in plain language.
- [Affordable Uptime Monitoring Tools That Don't Cut Corners](https://sentinel.rootstuff.io/blog/affordable-uptime-monitoring-tools): How to find genuinely affordable uptime monitoring — the pricing models that stay cheap, the hidden costs that make "cheap" expensive, and how the budget options really compare.
- [The Best Pingdom Alternatives in 2026 (Compared by Use Case)](https://sentinel.rootstuff.io/blog/pingdom-alternatives): Looking for a Pingdom alternative? Why teams switch, the criteria that actually decide the right tool, and how the main alternatives compare for free trackers, dev platforms and agencies.
- [The Best UptimeRobot Alternatives in 2026 (and How to Choose One)](https://sentinel.rootstuff.io/blog/uptimerobot-alternatives): Outgrowing UptimeRobot? Why teams move on, the criteria that actually matter, and how the main alternatives compare across free trackers, developer platforms and agency tools.
- [The Best Status Page Software in 2026 (and How to Choose One)](https://sentinel.rootstuff.io/blog/best-status-page-software): Skip the rankings. What a status page is really for, the criteria that decide the right tool, the three categories of status page software, and what to test before you commit.
- [Shopify Uptime Monitoring: Why Your Store Still Goes Down (and What to Watch)](https://sentinel.rootstuff.io/blog/shopify-uptime-monitoring): Shopify being up does not mean your store is working. Why Shopify stores still go down, what to actually monitor beyond the homepage, and how to catch problems before they cost sales.
- [The Best Uptime Monitoring Tools in 2026 (and How to Choose One)](https://sentinel.rootstuff.io/blog/best-uptime-monitoring-tools): Skip the cookie-cutter rankings. The criteria and categories that actually decide the best uptime monitoring tool for you, from free trackers to agency platforms, plus how the popular names compare.
- [Free Uptime Monitoring: What You Get, What You Don't, and When to Upgrade](https://sentinel.rootstuff.io/blog/free-uptime-monitoring): What free uptime monitoring actually covers, where free plans draw the line, how to set up solid monitoring without paying, and when upgrading finally earns its keep.
- [How to Monitor Website Uptime: A Step-by-Step Guide](https://sentinel.rootstuff.io/blog/how-to-monitor-website-uptime): A practical, step-by-step guide to setting up website uptime monitoring: what to monitor, how often to check, where to check from, alerts that don't cry wolf, and how to prove uptime.
- [How to Choose Uptime Monitoring Software for Your Agency (2026 Buyer's Guide)](https://sentinel.rootstuff.io/blog/choosing-uptime-monitoring-for-agencies): The criteria that actually matter when an agency picks a monitoring tool: multi-client organization, alert routing, white-label branding, reporting, check types and a pricing model that scales.
- [How to Onboard a New Client to Uptime Monitoring (An Agency Checklist)](https://sentinel.rootstuff.io/blog/agency-monitoring-onboarding-checklist): A repeatable, twenty-minute checklist for adding every new client to monitoring: what to gather, which monitors to add, naming and tagging, alert routing, status pages and the email that proves your value.
- [White-Label Uptime Monitoring: How Agencies Rebrand Monitoring as Their Own Service](https://sentinel.rootstuff.io/blog/white-label-uptime-monitoring): Turn monitoring from an invisible cost into a branded, billable service: branded status pages on custom domains, white-labeled client reports, on-brand alerting, and the economics of reselling it.
- [API Monitoring: How to Monitor REST APIs and Catch Failures Before Users Do](https://sentinel.rootstuff.io/blog/api-monitoring-guide): A practical guide to API monitoring: what to check beyond a 200, how to assert JSON payloads, alerting that doesn't cry wolf, and when synthetic flows beat single endpoints.
- [What Does 99.9% Uptime Actually Mean? (Plus the Five-Nines Cheat Sheet)](https://sentinel.rootstuff.io/blog/what-does-99-9-uptime-mean): What 99%, 99.9%, 99.99% and 99.999% uptime actually translate to in real downtime, plus how SLAs are calculated and what's realistic to promise clients.
- [Synthetic Monitoring vs Real User Monitoring: What's the Difference?](https://sentinel.rootstuff.io/blog/synthetic-monitoring-vs-real-user-monitoring): Synthetic monitoring and real user monitoring (RUM) sound similar but answer different questions. What each one does, where each one fails, and which you need first.
- [The Complete Guide to Uptime Monitoring in 2026](https://sentinel.rootstuff.io/blog/complete-guide-to-uptime-monitoring): Everything you need to know about uptime monitoring in 2026: the five check types, KPIs that matter, alert strategies that don't cry wolf, and how to pick the right tool.
- [Global Uptime Monitoring: Why Multi-Region Checks Matter](https://sentinel.rootstuff.io/blog/global-uptime-monitoring): Why single-region monitoring misses real outages, how multi-region checks catch regional failures, and what to look for in a global uptime tool.
- [How Much Does Website Monitoring Cost? A 2026 Pricing Breakdown](https://sentinel.rootstuff.io/blog/how-much-does-website-monitoring-cost): A clear breakdown of website monitoring pricing models, what drives cost, sample budgets for 5, 50, and 500 sites, and when paid plans pay for themselves.
- [How to Monitor Multiple Websites from One Dashboard](https://sentinel.rootstuff.io/blog/monitor-multiple-websites): Learn how to monitor dozens or hundreds of websites from a single dashboard with organized alerts, team permissions, and per-client status pages.
- [How to Reduce Website Downtime: 10 Proven Strategies](https://sentinel.rootstuff.io/blog/how-to-reduce-website-downtime): 10 actionable strategies to reduce website downtime, from external monitoring and DNS redundancy to staging environments and incident runbooks.
- [How to Build a Website Care Plan That Clients Will Pay For](https://sentinel.rootstuff.io/blog/website-care-plan-for-clients): A step-by-step guide to building website care plans with tiered pricing, monitoring, reporting, and strategies that turn maintenance into recurring revenue.
- [WordPress Uptime Monitoring: How to Keep Your Site Online 24/7](https://sentinel.rootstuff.io/blog/wordpress-uptime-monitoring): A practical guide to WordPress uptime monitoring: why WP sites go down, what to monitor, and how to set up external monitoring that actually catches problems.
- [Why Is My Website Down? A Non-Technical Guide to Diagnosing and Fixing It](https://sentinel.rootstuff.io/blog/why-is-my-website-down): A non-technical, step-by-step guide to diagnosing why your website is down, what to do right now, and how to make sure it never happens by surprise again.
- [The Freelancer's Guide to Monitoring Client Websites (Without Getting Overwhelmed)](https://sentinel.rootstuff.io/blog/freelance-website-monitoring-guide): A practical monitoring playbook for freelance web developers: minimum viable stack, alert triage, a 30-minute setup, and how to charge for uptime as a retainer.
- [How to Create an Uptime SLA for Client Websites](https://sentinel.rootstuff.io/blog/uptime-sla-for-client-websites): Learn how to define uptime guarantees, set realistic targets, and use monitoring data to back up your SLA commitments to clients.
- [The True Cost of Website Downtime (And How to Calculate It)](https://sentinel.rootstuff.io/blog/website-downtime-cost): Learn how to calculate the true cost of website downtime, including hidden costs like SEO damage and lost trust. Protect your revenue with proactive monitoring.
- [Website Monitoring for Agencies: The Complete Guide](https://sentinel.rootstuff.io/blog/website-monitoring-for-agencies): A complete guide to website monitoring for agencies. Learn how to manage client sites, organize alerts, and prove your value with uptime reports.
- [How to Set Up a Public Status Page for Your Clients](https://sentinel.rootstuff.io/blog/how-to-set-up-status-page): Learn how to set up a public status page that builds client trust, reduces support tickets, and communicates incidents transparently.
- [SSL Certificate Expiration: What Happens and How to Prevent It](https://sentinel.rootstuff.io/blog/ssl-certificate-expiration-prevention): Discover what happens when SSL certificates expire, how it impacts your site, and how automated monitoring prevents certificate-related outages.
- [Uptime Monitoring Explained: What It Is and How to Get Started](https://sentinel.rootstuff.io/blog/uptime-monitoring-explained): Everything you need to know about uptime monitoring: how it works, why check intervals matter, and how to set it up in 60 seconds.
- [DNS Monitoring: Protecting Your Domain from Hijacking and Outages](https://sentinel.rootstuff.io/blog/dns-monitoring-guide): Learn how DNS monitoring works, what records to watch, and how to protect your domain from hijacking, unauthorized changes, and outages.
- [Incident Management for Web Teams: From Alert to Resolution](https://sentinel.rootstuff.io/blog/incident-management-guide): A practical guide to incident management for web teams. Learn the incident lifecycle, escalation workflows, and how to reduce mean time to resolution.
- [7 Website Monitoring Best Practices Every Agency Should Follow](https://sentinel.rootstuff.io/blog/website-monitoring-best-practices): Seven practical website monitoring best practices for agencies, from multi-region checks to CI/CD integration and smart alerting strategies.

## Company

- [About](https://sentinel.rootstuff.io/about): Who builds Sentinel and why — a monitoring tool by rootstuff for the people who ship the web.
- [Contact](https://sentinel.rootstuff.io/contact): Get in touch with the Sentinel team for support, sales or beta access.

## Optional

- [Full blog content](https://sentinel.rootstuff.io/llms-full.txt): the complete text of every Sentinel blog article in one file