How to build SEO friendly Single Page Applications?
In order to make your Ajax website SEO friendly, you should implement the Dynamic Rendering recommendation. This will give you a guarantee that contents will always be correctly retrieved and indexed. While the old Ajax crawling scheme specification was only supported by a limited number of bots, the new Dynamic Rendering recommendation allows you to serve HTML snapshots to any bot.
Google offers an open-source project called RenderTron which is based on a headless version of Chrome. To use it, you have to install and maintain it yourself. An alternative is to use a service like SEO4Ajax which allows you to implement easily on your website the new Dynamic Rendering recommendation or the old Ajax crawling scheme specification without any hassle by copying/pasting the snippet of configuration provided in the site settings page.