Janome
Japanese morphological analysis engine.
Decision gist · record as of 2026-08-14
Yes, if you need to process Japanese text in Python. Janome is a mature, actively maintained, permissively licensed tool with no known vulnerabilities and low install friction. It's the right choice for projects that require Japanese morphological analysis without external system dependencies. Not relevant for non-Japanese text processing.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Python 3.7+ is required.
- Low install friction; the package is a pure Python wheel.
- Note that building from source consumes about 500 MB of memory during installation.
License · maintenance · safety
AL2 (permissive) — Licensed under Apache License 2.0 (permissive). The package also uses the MeCab-IPADIC dictionary and statistical model; see LICENSE.txt and NOTICE.txt for full details.
last release 2023-07-01 (1140 days) · last repo commit 2026-06-07 · 914 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 380,325 downloads/mo, #7,103 on PyPI
Alternatives
Verify before relying
pip install janome
from janome.tokenizer import Tokenizer
t = Tokenizer()
for token in t.tokenize('すもももももももものうち'):
print(token)- Whether the MeCab-IPADIC dictionary license imposes additional constraints beyond Apache 2.0 for commercial use.
- Current memory requirements for typical production workloads beyond the noted 500 MB build-time consumption.
- Performance characteristics and throughput on large-scale Japanese text processing tasks.
What it is and what it does
Janome is a morphological analyzer for Japanese text that runs entirely in Python without external compiled dependencies. It tokenizes Japanese sentences and annotates each token with part-of-speech tags and grammatical information using the MeCab-IPADIC dictionary. The package is designed for developers who need to process Japanese text in Python applications without installing system-level NLP tools.
The analyzer works by segmenting Japanese text (which lacks spaces between words) into meaningful tokens and providing linguistic metadata for each. It's used in search, text mining, and NLP pipelines where understanding the grammatical structure of Japanese is necessary. The package has been actively maintained since 2015 and remains in beta status.
Use it for
- Tokenize Japanese text for search indexing or full-text search applications.
- Extract part-of-speech information for Japanese language NLP tasks like sentiment analysis or text classification.
- Build Japanese text preprocessing pipelines for machine learning models that require morphological features.
- Analyze Japanese documents to identify nouns, verbs, and other grammatical elements for content analysis.
- Segment Japanese user input in chatbots or voice assistants before semantic processing.
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes, if you need to process Japanese text in Python.
Janome is a mature, actively maintained, permissively licensed tool with no known vulnerabilities and low install friction. It's the right choice for projects that require Japanese morphological analysis without external system dependencies. Not relevant for non-Japanese text processing.
Install
janome on PyPI
Before you install
Low install friction; the package is a pure Python wheel. Note that building from source consumes about 500 MB of memory during installation.
Python 3.7+ is required.
License in practice
Licensed under Apache License 2.0 (permissive). The package also uses the MeCab-IPADIC dictionary and statistical model; see LICENSE.txt and NOTICE.txt for full details.
Quickstart
pip install janome
from janome.tokenizer import Tokenizer
t = Tokenizer()
for token in t.tokenize('すもももももももものうち'):
print(token)Verify before relying
- Whether the MeCab-IPADIC dictionary license imposes additional constraints beyond Apache 2.0 for commercial use.
- Current memory requirements for typical production workloads beyond the noted 500 MB build-time consumption.
- Performance characteristics and throughput on large-scale Japanese text processing tasks.
Package facts
| License | AL2 permissive |
| Python support | Not specified |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | None |
| Maintenance | Actively maintained 1,140 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 380,325 / month, #7,103 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Development Status :: 4 - BetaLicense :: OSI Approved :: Apache Software LicenseNatural Language :: JapaneseProgramming Language :: Python :: 3.10Programming Language :: Python :: 3.7Programming Language :: Python :: 3.8Programming Language :: Python :: 3.9 |
Evidence: Janome-0.5.0-py2.py3-none-any.whl
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See also konoha · tinysegmenter · nagisa · mecab-python3 · SudachiPy · ja-ginza · mecab · rhoknp · ipadic · fugashi