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Custom extractor

You can customize the extraction process by using a custom extractor. When using this setup, instead of relying on its own internal extractor, Tolgee will use your script (written in JavaScript or TypeScript) to find and extract strings.


When using a custom extractor, you give up on the magic comments as it is part of the internal extractor logic.

Extractor structure

There is not much to know when writing a custom extractor. Here is the bare minimum file structure to follow:

import type { ExtractionResult } from '@tolgee/cli/extractor'

export default function (code: string, fileName: string): ExtractionResult {
const foundKeys = ... // some magic code

return {
keys: foundKeys,

Using your custom extractor

All commands using code extraction allow you to specify a --extractor option which takes a path to the extraction script to use. You can also configure it for the project via .tolgeerc.


When using TypeScript to write your extractor, you must also install ts-node as the CLI will use it to load the file.


tolgee extract print is a very helpful command to test and troubleshoot your extractor. It will dump all the keys it found and the warnings emitted to the console.

Type definitions

Here is the type definition of ExtractionResult:

type Warning = {
/** Warning message */
warning: string;
/** Line where the warning was emitted */
line: number;

type Key = {
/** Name of the key */
keyName: string;
/** Default value used when creating the key */
defaultValue?: string;
/** Namespace of the key */
namespace?: string;
/** Line where the key was found */
line: number;

type ExtractionResult = {
/** Keys found during the extraction */
keys: Key[];
/** Emitted warnings during the extraction */
warnings?: Warning[];