You will need version 4 or higher of `firefox`
to run Pencil as a Firefox Extension. Linux users will need version 4 or higher of either `firefox`, `iceweasel` or `xulrunner`,
or version 25 or higher of `palemoon`
The Windows installer and OS X archive has everything you need built-in. Windows, Linux, OS X & Firefox Packages are available for download from the Releases Page
You can also install the Firefox Add-on from the Mozilla Add-on Repository
To install the OS X package, unzip the archive and copy the `` folder t

Runtime alternatives

  • UptimeRobot

  • Monitors your websites every 5 minutes, totally free. Get alerts by e-mail, SMS, Twitter or RSS. Add up to 50 websites. Monitors can be refreshed for an instant check with a click. Supports https and authentication with user/password.

    tags: let-s-encrypt-support public-status-page twitter-notification uptime-monitoring
    platform: Online
  • Pingdom

  • Pingdom web site monitoring and other infrastructure for you and instantly let you know when anything goes wrong. Measure uptime, downtime, and the performance of your website as experienced by visitors.

    tags: performance-monitoring transactional-monitoring uptime-monitoring website-monitoring
    platform: Online Android iPhone

  • provides page change monitoring and notification services to Internet users worldwide. Anyone can use our service to monitor any website page for changes.

    tags: monitoring website-monitoring web-app monitor-changes
    platform: Online
  • StatusCake

  • StatusCake enables the visitor to track unlimited websites for free and get alerts when the site is down or having trouble. StatusCake also tracks performance over time so a webmaster can detect issues because they arise.

    tags: monitoring network-administration network-monitoring sms-notification status
    platform: Online
  • WebSite-Watcher

  • WebSite-Watcher detects website updates and highlights all changes in the text. WebSite-Watcher monitors web pages, password protected pages, discussion forums and much more.

    tags: rss website-updates webpage-monitoring web-page-monitoring
    platform: Windows
  • PageMon.Net

  • we're watching!

    tags: rss monitoring rss-feeds monitor-changes page
    platform: Online
  • WebMon

  • WebMon is a freeware web page update monitoring program - it saves you time and keeps you updated by automatically checking web pages to see if they have changed.

    tags: Discontinued Portable monitoring automatic webpage-monitoring
    platform: Windows Discontinued
  • Site24x7

  • Comprehensive website and web application monitoring:* simulate a real browser (Firefox) to check performance* services monitoring (FTP(S), DNS, PING, TCP, SSL, SMTP, POP)* user experience monitoring (browser load time per user-agent, response time in various platforms* response time and throughput of each web transaction with graphical representation for quick performance insight* performance stats by ISP* application performance monitoring (monitor Java, .NET and Ruby on Rails web transactions and drill down to offending code and pinpoint root cause of issues from the cloud)* cloud monitoring (Amazon EC2, RDS instances and S3 Bucket)* VMware Monitoring* server Monitoring (Linux, Windows)* On-Premise Poller to monitor intranets* monitor from 3G/4G carriers* DNS server monitoring* SSL certificate expiration monitoring* notifications via SMS, Email, Push Notifications, Twitter and RSS Feeds* mail server, Exchange, FTP monitoring* API, user management* Root Cause Analysis - a comprehensive report based on trace route, ping output, DNS reports and web page screenshots that gives you a conclusion on what caused the issue »

    tags: server-monitoring uptime-monitoring website-monitoring
    platform: Online
  • Monitis

  • Monitis is a Cloud monitoring and IT analytics service offering Website Monitoring, Server Monitoring, Network Monitoring, Application Monitoring, Cloud Monitoring, and Custom Monitoring.

    tags: application-monitoring cloud-monitoring load-testing network-monitoring performance-testing
    platform: Online
  • OnWebChange

  • Track web page changes in any web page daily for free users, every 30 mins for paid users - no RSS or Atom required. Receive notifications via Email, Notifo, Instant Message and SMS.

    tags: website-monitoring notifications monitor-changes notify web-page
    platform: Online
  • Port Monitor

  • Port Monitor is an easy and online tool that does website and server monitoring for you 24/7 every 60 seconds and sends you or your co-workers instant email/push notifications when something goes wrong.

    tags: notifications server-monitoring uptime-monitoring website-monitoring
    platform: Online
  • PushMon

  • PushMon is a new kind of cloud-based monitoring system. Instead of checking public facing servers on a regular basis, PushMon will wait for pings from the objects being monitored. These objects are usually batch jobs, scheduled/cron scripts, backups, or test scripts, but really are anything that has access to the internet and can call a URL on a regular basis. If PushMon does not receive the URL "ping" by the specified schedule (like every hour, or every day or even by 5:00 PM every Fri), it will send an alert (email, IM, SMS, Twitter and/or phone call). We can monitor your database backups, your cron scripts, your background tests, your internet connectivity, your batch jobs, and a lot more. We also have an advanced but easy to use scheduling feature to alert you of problems as soon as possible. »

    tags: cloud-monitoring job-monitoring script-monitoring cron-monitoring batch-monitoring
    platform: Online
  • Dotcom-Monitor

  • Website & Web Application Monitoring

    tags: monitoring website-monitoring web-application web-applications application-monitoring
    platform: Online
  • Binary Canary

  • Website monitoring service that offers a comprehensive free plan with:* escalation levels (if a first-responder contact doesn't acknowledge the downtime, another contact will be alerted)* search for text on the website to detect defacing/hacking in addition to downtime

    tags: monitoring server-monitoring uptime-monitoring webmaster-tools website-monitoring
    platform: Online
  • Versionista

  • Versionista was designed for the rough-and-tumble world of today's Web, where subtle edits can offer actionable tactical advantage. It lets you monitor entire Web sites and receive e-mail alerts when changes that meet your filters are met. It tracks and archives any entity's total online presence, including social media, blogs, and other Web sites. It lets you follow the evolution of any site, and know when important changes occur — even to deeply nested pages.

    tags: website-monitoring monitor-changes web-scraping webpage-monitoring web-scraper
    platform: Online