isbnlib provides several useful methods and functions to validate, clean, transform, hyphenate and get metadata for ISBN strings.



isbnlib is a (pure) python library that provides several useful methods and functions to validate, clean, transform, hyphenate and get metadata for ISBN strings. Its origin was as the core of isbntools.

This short version, is suitable to be include as a dependency in other projects. Has a straightforward setup and a very easy programmatic api.

Runs on py26, py27, py33, py34, py35, pypy and pypy3.


Typical usage (as library):

import isbnlib

Just for fun, suppose I want the most spoken about book with certain words in his title. For a quick-and-dirty solution, enter the following code in a file and save it as

#!/usr/bin/env python
import sys
from isbnlib import *

query = sys.argv[1].replace(' ', '+')
isbn = isbn_from_words(query)

print("The ISBN of the most `spoken-about` book with this title is %s" % isbn)
print("... and the book is:")

Then in a command line (in the same directory):

$ python 'noise'

In my case I get:

The ISBN of the most `spoken-about` book with this title is 9780143105985

... and the book is:

{'Publisher': u'Penguin Books', 'Language': u'eng', 'Title': u'White noise',
'Year': u'2009', 'ISBN-13': u'9780143105985', 'Authors': u'Don DeLillo ;
introduction by Richard Powers.'}

Have fun!


From the command line enter (in some cases you have to preced the command with sudo):

$ pip install isbnlib


$ easy_install isbnlib


$ pip install isbnlib-3.6.7.tar.gz

(first you have to download the file!)

If you use linux systems, you can install using your distribution package manager (all major distributions have packages python-isbnlib and python3-isbnlib), however (usually) are very old and don’t work well anymore!

For Devs


The official form of an ISBN is something like ISBN 979-10-90636-07-1. However for most applications only the numbers are important and you can always masked them if you need (see below). This library works mainly with ‘striped’ ISBNs (only numbers and X) like ‘0826497527’. You can strip an ISBN’s like string by using canonical(isbnlike). You can ‘mask’ the ISBN by using mask(isbn). So in the examples below, when you see ‘isbn’ in the argument, it is a ‘striped’ ISBN, when the argument is an ‘isbnlike’ it is a string like ISBN 979-10-90636-07-1 or even something dirty like asdf 979-10-90636-07-1 bla bla.

Two important concepts: valid ISBN should be an ISBN that was built according with the rules, this is distinct from issued ISBN that is an ISBN that was already issued to a publisher (this is the usage of the libraries and most of the web services). However, probably by legal reasons, merges the two! So, according to, ‘9786610326266’ is not valid (because the block 978-66... has not been issued yet, however if you use is_isbn13('9786610326266') you will get True (because ‘9786610326266’ follows the rules of an ISBN). But the situation is even murkier, try meta('9786610326266') and you will see that this ISBN was already used!

If possible, work with ISBNs in the isbn-13 format (since 2007, only are issued ISBNs in the isbn-13 format). You can always convert isbn-10 to isbn-13, but not the reverse. Read more about ISBN at

API’s Main Namespaces

In the namespace isbnlib you have access to the core methods:

Validates as ISBN-10.
Validates as ISBN-13.
Transforms an isbn-13 to isbn-10.
Transforms an isbn-10 to isbn-13.
Keeps only numbers and X. You will get strings like 9780321534965.
Cleans ISBN (only legal characters).
notisbn(isbnlike, level='strict')
Check with the goal to invalidate isbn-like.
get_isbnlike(text, level='normal')
Extracts all substrings that seem like ISBNs (very useful for scraping).
get_canonical_isbn(isbnlike, output='bouth')
Extracts ISBNs and transform them to the canonical form.
Transforms an isbnlike string into an EAN13 number (validated canonical ISBN-13).
Gets the language or country assigned to this ISBN.
mask(isbn, separator='-')
Mask (hyphenate) a canonical ISBN.
meta(isbn, service='default', cache='default')
Gives you the main metadata associated with the ISBN. As service parameter you can use: 'wcat' uses (no key is needed), 'goob' uses the Google Books service (no key is needed), 'isbndb' uses the service (an api key is needed), 'openl' uses the api (no key is needed), merge uses a merged record of wcat, goob and openl records (no key is needed) and is the default option. You can get an API key for the service here_. You can enter API keys with isbnlib.config.add_apikey(service, apikey). The output can be formatted as bibtex, msword, endnote, refworks, opf or json (BibJSON) bibliographic formats with isbnlib.registry.bibformatters. cache only allows two values: ‘default’ or None. You can change the kind of cache by using isbnlib.registry.set_cache (see below). Now, you can extend the functionality of this function by adding pluggins, more metadata providers or new bibliographic formatters (check for available pluggins).
editions(isbn, service='merge')
Returns the list of ISBNs of editions related with this ISBN. By default uses ‘merge’ (merges ‘openl’ with ‘thingl’), but other providers are available: ‘openl’ users Open Library, ‘thingl’ (uses the service ThingISBN from LibraryThing) and ‘any’ (first tries ‘openl’, if no data, tries ‘thingl’).
Returns the most probable ISBN from a list of words (for your geographic area).
Returns a list of references from Google Books multiple references.
Returns a DOI’s ISBN-A from a ISBN-13.
Returns metadata formated as BibTeX for a given DOI.
Renames a file using metadata from an ISBN in his filename.
Returns a small description of the book. Almost all data available are for US books!
Returns a dictionary with the url for cover. Almost all data available are for US books!

See files test_core and test_ext for a lot of examples.

The exceptions raised by these methods can all be catched using ISBNLibException.

You can extend the lib by using the classes and functions exposed in namespace, namely:

  • WEBService a class that handles the access to web services (just by passing an url) and supports gzip. You can subclass it to extend the functionality... but probably you don’t need to use it! It is used in the next class.
  • WEBQuery a class that uses WEBService to retrieve and parse data from a web service. You can build a new provider of metadata by subclassing this class. His main methods allow passing custom functions (handlers) that specialize them to specific needs (data_checker and parser). It implements a throttling mechanism with a default rate of one call per second per service.
  • Metadata a class that structures, cleans and ‘validates’ records of metadata. His method merge allows to implement a simple merging procedure for records from different sources. The main features can be implemented by a call to stdmeta function!
  • vias exposes several functions to put calls to services, just by passing the name and a pointer to the service’s query function. vias.parallel allows to put threaded calls. You can use vias.serial to make serial calls and vias.multi to use several cores. The default is vias.serial, but you can change that in the conf file.
  • bouth23 (DEPRECATED) a small module to make it possible the code to run in bouth python 2 and python 3. It will disappear in the next major version!. See for a built-in alternative to bouth23.

The exceptions raised by these methods can all be catched using ISBNLibDevException. You should’t raise this exception in your code, only raise the specific exceptions exposed in whose name end in Error.

In you can find several methods, that we found very useful, some of then are only used in isbntools (an app and framework that uses isbnlib).

With isbnlib.registry you can change the metadata service to be used by default (setdefaultservice), add a new service (add_service), access bibliographic formatters for metadata (bibformatters), set the default formatter (setdefaultbibformatter), add new formatters (add_bibformatter) and set a new cache (set_cache) (e.g. to switch off the chache set_cache(None)). The cache only works for calls through isbnlib.meta. These changes only work for the ‘current session’, so should be done always before calling other methods.

Finally, from isbnlib.config you can read and set configuration options: change timeouts with setsocketstimeout and setthreadstimeout, access api keys with apikeys and add new one with add_apikey and access and set generic and user-defined options with options and set_option.

Let us concretize the last point with a small example.

Suppose you want a small script to get metadata using formated in BibTeX.

To use this service you need an api-key (get it here_). A minimal script would be:

from isbnlib import meta
from isbnlib.config import add_apikey
from isbnlib.registry import bibformatters

SERVICE = 'isbndb'
APIKEY = 'THiSIsfAKe'  # <-- replace with YOUR key

# register your key
add_apikey(SERVICE, APIKEY)

# now you can use the service
isbn = '9780446310789'
bibtex = bibformatters['bibtex']
print(bibtex(meta(isbn, SERVICE)))

All these classes follow a simple design pattern and, if you follow it, will be very easy to integrate your classes with the rest of the lib.


You can extend the functionality of the library by adding pluggins (for now, just new metadata providers or new bibliographic formatters).

Start with this template and follow the instructions there. For inspiration take a look at wcat, goob or merge.

After install, your pluggin will blend transparently in isbnlib.

Merge Metadata

The original quality of metadata, at the several services, is not very good! If you need high quality metadata in your app, the only solution is to use polling & merge of several providers and a lot of cleaning and standardization for fields like Authors and Publisher. A simple merge provider is now the default in isbnlib.meta. It gives priority to wcat but overwrites the Authors, Publisher and Year fields with values from goob (if available) or openl. Uses the merge method of Metadata and parallel calls to services.

You can change that by using vias‘s other methods (e.g. isbnlib.config.set_option('VIAS_MERGE', 'multi').

You can write your own merging scheme by creating a new provider (see merge for an example).


These classes are optimized for one-calls to services and not for batch calls.

Known Issues

  1. The meta method sometimes give a wrong result (this is due to errors on the chosen service), in alternative you could try one of the others services.
  2. The isbnlib works internally with unicode, however this doesn’t solve errors of lost information due to bad encode/decode at the origin!
  3. Periodically, agencies, issue new blocks of ISBNs. The range of these blocks is on a database that mask uses. So it could happen, if you have a version of isbnlib that is too old, mask doesn’t work for valid (recent) issued ISBNs. The solution? Update isbnlib often!
  4. Calls to metadata services are cached by default. You can change that by calling isbnlib.meta(isbn, service='default', cache=None)

Any issue that you would like to report, please do it at github or post a question on stackoverflow (with tag isbnlib).



Coverage Graph Built Status Windows Built Status

How to Contribute

isbnlib has a very small code base, so it is a good project to begin your adventure in open-source...

Main Steps

  1. Make sure you have a GitHub account
  2. Submit a ticket for your issue or idea, on GitHub issues (if possible wait for some feedback before any serious commitment... :)
  3. Fork the repository on GitHub
  4. pip install -r requirements-dev.txt
  5. Do your code... (remember the code must run on python 2.6, 2.7, 3.3, 3.4, pypy and be OS independent) (you will find very handy for this!)
  6. Write tests for your code using nose and put then in the directory isbnlib/test
  7. Pass all tests and with coverage > 90%. Check the coverage in Coveralls.
  8. Check if all requirements are fulfilled!
  9. Make a pull request on github...


If you don’t have experience in these issues, don’t be put off by these requirements, see them as a learning opportunity. Thanks!

For full instructions read the CONTRIBUTING doc.