Local server configuration¶

When using a local LanguageTool server you can tune its behaviour by passing a config dictionary to LanguageTool. Internally, the dictionary is validated and written to a temporary *.cfg file that is passed to the Java process via --config.

Note

config is only available for local servers. Combining config with remote_server raises ValueError.

Quick example¶

import language_tool_python

with language_tool_python.LanguageTool(
    "en-US",
    config={
        "cacheSize": 1000,
        "cacheTTLSeconds": 300,
        "maxTextLength": 100_000,
        "pipelineCaching": True,
    },
) as tool:
    print(tool.correct("A sentence with a error in the Hitchhiker's Guide tot he Galaxy"))
    # → A sentence with an error in the Hitchhiker's Guide to the Galaxy

Accepted keys¶

Limits¶

Key	Type	Description
`maxTextLength`	`int`	Maximum number of characters accepted per request. Requests exceeding this limit are rejected.
`maxTextHardLength`	`int`	Hard character limit that applies even to privileged users with a special token. Requests exceeding this limit are rejected.
`maxCheckTimeMillis`	`int`	Maximum time in milliseconds allowed for a single check request.
`maxErrorsPerWordRate`	`int \| float`	If the ratio of errors to words exceeds this value, the check is aborted.
`maxSpellingSuggestions`	`int`	Maximum number of spelling suggestions returned per error. Applies to Hunspell-based languages only.
`maxCheckThreads`	`int`	Maximum number of threads used concurrently for checking.
`maxWorkQueueSize`	`int`	Maximum number of requests that can queue up before new requests are rejected.

Rate limiting¶

Key	Type	Description
`requestLimit`	`int`	Maximum number of requests allowed within `requestLimitPeriodInSeconds`.
`requestLimitInBytes`	`int`	Maximum total request body size in bytes within the rate-limit window.
`timeoutRequestLimit`	`int`	Maximum number of timed-out requests before the server starts rejecting new ones.
`requestLimitPeriodInSeconds`	`int`	Duration of the rate-limiting window in seconds.

Pipeline caching¶

Key	Type	Description
`cacheSize`	`int`	Number of sentences to keep in the internal cache (default: 0, disabled).
`cacheTTLSeconds`	`int`	How many seconds sentences are kept in the cache (default: 300 if `cacheSize` is set).
`pipelineCaching`	`bool \| int`	Enable internal pipeline caching for faster repeated checks.
`maxPipelinePoolSize`	`int`	Maximum number of cached pipelines.
`pipelineExpireTimeInSeconds`	`int`	Expiry time for cached pipelines in seconds.
`pipelinePrewarming`	`bool \| int`	Fill the pipeline cache on startup to reduce first-request latency. Can significantly slow down server start.

External models¶

All path values must point to existing files or directories, the path is validated when LanguageToolConfig is instantiated.

Key	Type	Description
`languageModel`	`str \| Path`	Path to a directory containing `1grams`, `2grams`, and `3grams` sub-directories (one Lucene index each) per language. Activates the confusion rule for supported languages.
`fasttextModel`	`str \| Path`	Path to a fastText language-identification model file.
`fasttextBinary`	`str \| Path`	Path to the fastText binary executable.
`rulesFile`	`str \| Path`	Path to an XML file containing custom rules.

Access control¶

Key	Type	Description
`blockedReferrers`	`str \| list \| tuple \| set`	Comma-separated referrer URLs (or a collection) that are blocked from using the server.
`premiumOnly`	`bool \| int`	Activate only the premium rules, ignoring all free rules.
`trustXForwardForHeader`	`bool \| int`	Trust the `X-Forwarded-For` header for rate limiting (use only behind a trusted reverse proxy).

Miscellaneous¶

Key	Type	Description
`disabledRuleIds`	`str \| list \| tuple \| set`	Comma-separated rule IDs (or a collection) that are disabled globally for all requests.
`suggestionsEnabled`	`bool \| int`	Whether to compute replacement suggestions. Disabling this speeds up checking when suggestions are not needed.

Language-specific keys¶

In addition to the keys above, you can configure per-language spell-checking by using keys of the form lang-<code> or lang-<code>-dictPath:

Key pattern	Type	Description
`lang-<code>`	`str`	Display name of the language (e.g. `lang-tr=Turkish`). Registers a spellcheck-only language that LT does not natively support.
`lang-<code>-dictPath`	`str \| Path`	Absolute path to the Hunspell `.dic` file for the given language code (e.g. `lang-tr-dictPath`). The same directory must also contain a `common_words.txt` file listing the 10,000 most common words (used for language detection). The path must point to an existing file.

API reference¶

See LanguageToolConfig for the full class documentation.