We have done some improvements to coverstore, the Open Library book covers service, recently.
Now it is possible to access book covers by all the available identifiers. For example:
Accessing covers by ISBNs is insensitive to hyphens now. For example, all the following URLs point to the same cover and this works even if the ISBN is specified with hyphens in the edition record.
Please refer to the Open Library Covers API for more details.
We have built a secondary database for storing edition identifiers to cover ID mapping to make the accessing covers faster. Because of this there is some delay between adding an identifier to an edition record and accessing the cover using the newly added identifier. The delay is usually couple of seconds.
Please note that this API is intended for displaying covers on public facing websites and not for bulk download. To download the book covers in bulk, please refer to Bulk Access section of the API documentation.
We have recently noticed that some bots are downloading book covers by ISBNs at very high rate and that effected the performance of the system badly. We have added rate-limiting to limit the number of requests per IP address. The current allowed limit is 100 requests per IP for every 5 minutes. The limit is applicable only for cover accesses by various identifiers and there is no limit of accessing covers by cover ID.
This limit should be good enough for linking covers on public facing websites. Please consider using Open Library Books API if your website demands more. Since the Books API provides book cover URLs using cover IDs, the rate-limit won’t be applicable.
Please get in touch with us if you need any assistance in using this API to show book covers on your website.