The project described in the paper is https://simdjson.org/.

PyPI: https://pypi.org/project/pysimdjson/

There's a rust port: https://github.com/simd-lite/simd-json

... From ijson https://pypi.org/project/ijson/#id3 which supports streaming JSON:

> Ijson provides several implementations of the actual parsing in the form of backends located in ijson/backends: [yajl2_c, yajl2_cffi, yajl2, yajl, python]