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yajl-py is a Pure Python wrapper (implemented using ctypes) to the excellent Yajl (Yet Another JSON Library) C library.

yajl and yajl-py, allow for fast stream parsing of JSON files, which enables the parsing of large files, that would not fit in memory.


  • python 2.7+, python 3.3+
  • yajl

To run the tests you also require:

  • make (to run make test)
  • nose (debian package == python-nose)
  • mock (pip install mock)


From within the current directory run:

pip install .

To install from pypi:

pip install yajl-py


The examples directory contains full featured JSON Parsers built using yajl and yajl-py. See examples/README.rst for more info.

Notes around strings, python 3, and yajl-py

TLDR; if using python3, yajl-py expects bytes and not strings

Python 3 fixed a whole string of issues with strings. Due to these fixes somethings taken for granted in python 2 are now explicit in python 3. The major change that affects yajl-py is related to a decision made within ctypes.

Strings going and coming from the ctypes interface to c-code are now bytes. Although we can make an explicit decision to decode and encode strings transparently to latin-1 or utf-8, this is an arbitrary choice. Even though it can be coded in such a way to make the encoding configurable, the decision has been made to keep with the decision made by ctypes and hence put the onus on the developer to decode/encode the input/output as necessary.


The following people provided valuable contributions to this library: