@jackdewey Thanks for your hints. Now I disabled the dynamic thumbnail generation and the site uses locally stored thumbs instead. And, to be honest, it might even be the better solution regarding loading time and the screen-shotted websites do not change that rapidly. A manual update twice a year should be enough for my use case.
Nevertheless, it would be a nice feature to have the ability to use a (free, at least for a little to medium amount of requests per month) dynamic thumbnail service via https – for both the requesting site and the screen-shotted site. There are so many services similar to STW suggested by @puravida1976 (e.g. https://www.programmableweb.com/category/screenshots/api). Of course, most of them offer only very limited functionality for free, but maybe you can find one that is suitable at least for operators of smaller websites among the Link Library users?
– https://www.pagelr.com/Plans
– http://www.sitesnapr.com/index.html#price
– https://market.mashape.com/thumbnail/website-screenshots
– https://market.mashape.com/handtrix/website-screenshot
Best regards,
Manuel.
