Your uptime monitor cried wolf. Again.
Multi-region uptime monitoring that confirms downtime from 4 global regions before paging you — so every notification means a real outage.
Free plan includes commercial use — monitor client and production sites.
See a live status page — we monitor FourSight with FourSightIncident detected
api.example.com
Confirming across all probe regions before paging you…
Real outage confirmed
4 of 4 regions agree · Alert sent in 42s
What is FourSight?
FourSight is a multi-region uptime monitoring service that checks websites, APIs, and infrastructure from four probe regions — United States, Canada, Europe, and Asia-Pacific — and applies a per-rule quorum policy before alerting. Eight monitor types cover HTTP, ping, SSL, DNS, port, keyword, domain expiry, and heartbeat/cron checks, with a free plan that includes HTTP and ping monitoring.
Quick Start
Start monitoring in under 60 seconds
Add URL
Enter your app, API, or website URL.
Choose Regions
Check uptime from multiple global regions for real-world accuracy.
Get Alerts
Receive instant email, Slack, or webhook alerts when something breaks.
We monitor FourSight with FourSight — watch the live status page. Built and operated by TetraCore, the Ohio software studio.
Monitor Types
Eight check types. Four global regions.
From simple pings to port-level protocol validation — FourSight covers every angle of site and infrastructure reliability.
HTTP & Uptime Checks
Monitor any URL with configurable expected status codes, headers, response body validation, and custom timeouts.
Keyword / Content
Verify pages contain (or don't contain) specific text — catch defacements, broken deploys, and content changes instantly.
SSL Certificate Monitoring
Track certificate expiry with 30, 14 & 7-day alerts so you never serve an insecure warning to visitors.
Learn more →
DNS Drift Detection
Monitor DNS record changes and get alerted when records drift from expected values across any record type.
Learn more →
Domain Expiry Tracking
Track domain registration expiry via RDAP with alerts at 90, 60, 30 & 10 days before your domain lapses.
Learn more →
Ping Monitoring
TCP-based latency and packet loss measurement across multiple attempts — ideal for infrastructure health checks.
Port Monitoring
TCP/UDP port checks with banner detection, send/expect regex, and presets for SMTP, IMAP, FTP, SSH, DNS & more.
Learn more →
Heartbeat Monitoring
Monitor recurring signals from background jobs, cron scripts, webhooks, and scheduled tasks using fixed intervals or 5-field cron expressions.
Learn more →
Multi-Region Validation
Checks run from US, Canada, Europe & APAC with quorum-based consensus to eliminate false positives from regional outages.
Alerting
Get notified your way
Four notification channels so your team never misses a beat — from inbox to Slack to custom webhooks.
Email Alerts
Instant email notifications with rich HTML templates, configurable per-monitor rules, and one-click unsubscribe.
Slack Integration
Real-time alerts to any Slack channel with Block Kit formatting, status emojis, and deep-link buttons to incidents.
Webhooks
JSON payloads with HMAC-SHA256 signing, event-type headers, and exponential backoff retries for reliable delivery.
SMS Notifications
Text message alerts to any phone number with E.164 formatting, carrier-compliant opt-in, and instant delivery.
How it works
Up and running in three steps
Add a monitor
Enter a URL, choose a check type (HTTP, SSL, DNS, Port & more), set the interval. Done in 30 seconds.
We check globally
Probes in 4 regions ping your endpoint on schedule and use quorum consensus to confirm real issues.
Get alerts + insights
If something fails, you're notified via email, Slack, webhook, or SMS. Full history and uptime stats are always available.
Platform
Designed to be dependable
Public Status Pages
Branded, subscriber-ready pages your customers can bookmark. Add custom CSS, display maintenance banners, and let users subscribe to incident updates.
Maintenance Windows
Schedule one-time or recurring maintenance to suppress alerts and incidents. Supports daily, weekly & monthly RRULEs with configurable behavior.
Incident Management
Auto-created incidents with severity levels (critical, major, minor), status updates (investigating → resolved), and a full event timeline.
Multi-Region Consensus
Checks run from 4 regions with quorum-based voting. A single region going offline won't trigger false alerts for your team.
Multi-Tenant Organizations
Invite your team, assign roles (owner, admin, member), and manage monitors, status pages, and billing together.
Configurable Intervals
Free: 5-minute intervals. Starter: 1-minute intervals. Growth/Pro: 30-second intervals. Scale: 15-second intervals.
Live Demo
See FourSight in action
Browse our live demo status page — real uptime data, latency charts, and incident history, exactly as your users would see it.
Pricing
Simple, transparent pricing
Start free. Upgrade when you need more monitors, faster checks, or advanced features.
Free
$0 forever
- Up to 10 monitors
- HTTP & Ping monitor types
- 5-minute check intervals
- Multi-region validation (4 regions)
- Email alerts only
Starter
$16/month
- Up to 50 monitors (expandable)
- HTTP & Ping monitor types
- 1-minute check intervals
- Multi-region validation (4 regions)
- Email, Slack & Webhook alerts
Growth
$40/month
- Up to 100 monitors (expandable)
- All 8 monitor types incl. Heartbeat (HTTP, Ping, SSL, DNS, Domain, Keyword, Port, Heartbeat)
- 30-second check intervals
- Multi-region validation (4 regions)
- Email, Slack & Webhook alerts
Pro
$80/month
- Up to 250 monitors (expandable)
- All 8 monitor types incl. Heartbeat
- 30-second check intervals
- Multi-region validation (4 regions)
- Email, Slack, Webhook & SMS alerts
Scale
$160/month
- 500+ monitors
- All 8 monitor types incl. Heartbeat
- 15-second check intervals
- Multi-region validation (4 regions)
- All alert channels + phone support
FAQ
Common questions
What is FourSight?
FourSight is a multi-region uptime monitoring service built and operated by TetraCore. It checks websites, APIs, and infrastructure from 4 probe regions (United States, Canada, Europe, Asia-Pacific), applies a per-rule quorum policy before alerting, opens incidents with severity levels, notifies you by email, Slack, webhook, or SMS depending on plan, and publishes public status pages.
Is there a free plan, and what does it include?
Yes. The Free plan costs $0 with no credit card and no trial expiry. It includes up to 10 monitors, HTTP and Ping check types, 5 minute check intervals, validation from all 4 probe regions, email alerts, 1 public status page, and 24-hour history. Commercial use is allowed.
How many regions does FourSight check from?
Four: United States, Canada, Europe, Asia-Pacific. Every plan, including Free, runs checks from all 4 regions — multi-region validation is not a paid add-on.
What monitor types does FourSight support, and which plan unlocks them?
Eight: HTTP/HTTPS, Ping, SSL certificate, DNS, Domain expiry, Keyword/content, Port (TCP/UDP), Heartbeat/cron. Free ($0) and Starter ($16/mo) include HTTP and Ping only. Growth ($40/mo), Pro ($80/mo), and Scale ($160/mo) unlock all eight. Check intervals are 5 minutes on Free, 1 minute on Starter, 30 seconds on Growth and Pro, and 15 seconds on Scale.
How does quorum (consensus) alerting work?
Every check runs from all 4 regions in parallel. Each notification rule has a regional quorum setting that decides how many regions must report the failure before that rule alerts: Any region (the default), Two or more, or Majority. Raising the quorum filters out single-region network blips; the default alerts fastest.
Running monitoring for clients? White-label it.
The Scale plan puts status pages on your clients' own domains with your branding, groups monitors per client, and keeps a year of history for monthly uptime reports — one flat price, no per-seat surprises.
Start monitoring in minutes
No credit card required. 10 free monitors. Alerts via email, Slack, webhooks & SMS.