Best On-page Chechker tool

[JohnVilson]

"MOZ" is one of the best tool for on-site SEO. MOZ is paid tool which provides not only all on-page errors but also guide you about how to fix all error.

[pathannishat]

Yes MOZ and SEO Xplorer also good tool for seo also you can check smallseo tools

[Sunainapaul11]

Some of the best On page checker tool are: SEOPTIMER, MOZ and W3Cvalidator. You can get the complete analysis of your website within an instant.

[DevnathSekar]

There are number of On-page checker tool available but the best one is SEOMOZ. Every SEO expert prefer to use this tool.

[josephinek]

Go through the following links:
>seositecheckup.com
>seorch.eu
>onpageseotool.com
>woorank.com

[dakshinfo]

One of the best and important tool for On Page that is "MOZ". MOZ is paid tool which provides not only all on-page errors but also guide you about how to fix all error.

[vishistsingh]

No doubt Moz, one of the best seo tool for on page optimization but it is paid. Apart from Moz, there are many tools for on-page optimization which are free and provides best on page optimization are.
1. Seoptimer
2. W3C validator

[dexterousweb]

Moz is the best tool for seo on-page checking tool. It will indicate your errors and help you to get more awareness in search engine.I also like woorank to check onpage errors for a website

[cwvps]

I prefer Wordstream and Ubersuggest.

[Talukdar]

These are some best on-page checker tools
http://www.internetmarketingninjas.com/seo-tools/free-optimization/