1. UptimeRobot
(https://i.amz.mshcdn.com/lq04DKNABn4mlPkR7dCWtolbKGg=/fit-in/1200x9600/http%3A%2F%2Fmashable.com%2Fwp-content%2Fuploads%2F2010%2F04%2Fuptimeuptimerobot.jpg)
2. Pingdom
(https://i.amz.mshcdn.com/qhziY0sVwKnAzBrcXF3QAYGq9wY=/fit-in/1200x9600/http%3A%2F%2Fmashable.com%2Fwp-content%2Fuploads%2F2010%2F04%2Fuptimepingdom.jpg)
3. Mon.itor.us
(https://i.amz.mshcdn.com/e89aDGkCL8Znz9Ps-cfZW-7exKw=/fit-in/1200x9600/http%3A%2F%2Fmashable.com%2Fwp-content%2Fuploads%2F2010%2F04%2Fuptimemonitorus.jpg)
4. InternetSeer
(https://i.amz.mshcdn.com/8wngeUsxGbGF5ZL2GUxQfddNxz8=/fit-in/1200x9600/http%3A%2F%2Fmashable.com%2Fwp-content%2Fuploads%2F2010%2F04%2Fuptimeinternetseer.jpg)
5. Uptrends
(https://i.amz.mshcdn.com/3MUFWF7dC-ulKE5RGBXqI51WwQw=/fit-in/1200x9600/http%3A%2F%2Fmashable.com%2Fwp-content%2Fuploads%2F2010%2F04%2Fuptimeuptrends.jpg)
6. BasicState
(https://i.amz.mshcdn.com/5Gvj7LbYovjHaRaT0QkgHtU7zUY=/fit-in/1200x9600/http%3A%2F%2Fmashable.com%2Fwp-content%2Fuploads%2F2010%2F04%2Fuptimebasicstate_picnik.jpg)
7. Montastic
(https://i.amz.mshcdn.com/Ql0pnIF83CALJWAP7oeKuaRF3Ng=/fit-in/1200x9600/http%3A%2F%2Fmashable.com%2Fwp-content%2Fuploads%2F2010%2F04%2Fuptimemontastic.jpg)
8. Are My Sites Up?
(https://i.amz.mshcdn.com/hrLcsh68M5FMvuAZw17V0npq_L4=/fit-in/1200x9600/http%3A%2F%2Fmashable.com%2Fwp-content%2Fuploads%2F2010%2F04%2Fuptimearemysitesup.jpg)
9. Site24x7
(https://i.amz.mshcdn.com/ccb_C7UReZ3LlpRhDPyzaaD0ye4=/fit-in/1200x9600/http%3A%2F%2Fmashable.com%2Fwp-content%2Fuploads%2F2010%2F04%2Fuptimesite247_picnik.jpg)
10. 100Pulse
(https://i.amz.mshcdn.com/lCVv5eM20-PdgO-Xyg6_GCy9KJA=/fit-in/1200x9600/http%3A%2F%2Fmashable.com%2Fwp-content%2Fuploads%2F2010%2F04%2Fuptime100pulse_picnik.jpg)
Source: https://mashable.com/2010/04/09/free-uptime-monitoring/#BpCOnv0L6kqX