📝 YouTube Transcript API

⚠️WARNING ⚠️

This library uses undocumented YouTube API, so it's possible that it will stop working at any time. Use at your own risk.

📖 Introduction

Java library which allows you to retrieve subtitles/transcripts for a YouTube video. It supports manual and automatically generated subtitles and does not use headless browser for scraping. Inspired by Python library.

🤖 Features

✅ Manual transcripts retrieval

✅ Automatically generated transcripts retrieval

✅ Transcript translation

✅ Transcript formatting

✅ Easy-to-use API

✅ Minimal dependencies (Jackson for XML/JSON processing and Apache Commons Text for XML tag unescaping)

✅ Supports Java 11 and above

🛠️ Installation

Maven

<dependency>
    <groupId>io.github.thoroldvix</groupId>
    <artifactId>youtube-transcript-api</artifactId>
    <version>0.1.0</version>
</dependency>

Gradle

implementation 'io.github.thoroldvix:youtube-transcript-api:0.1.0'

Gradle (kts)

implementation("io.github.thoroldvix:youtube-transcript-api:0.1.0")

🔰 Getting Started

To start using YouTube Transcript API, you need to create an instance of YoutubeTranscriptApi by calling createDefault method of TranscriptApiFactory. Then you can call listTranscripts to get a list of all available transcripts for a video:

// Create a new default YoutubeTranscriptApi instance
YoutubeTranscriptApi youtubeTranscriptApi = TranscriptApiFactory.createDefault();

// Retrieve all available transcripts for a given video
TranscriptList transcriptList = youtubeTranscriptApi.listTranscripts("videoId");

TranscripList is an iterable which contains all available transcripts for a video and provides methods for finding specific transcripts by language or by type (manual or automatically generated).

TranscriptList transcriptList = youtubeTranscriptApi.listTranscripts("videoId");

// Iterate over transcript list
for(Transcript transcript : transcriptList) {
    System.out.println(transcript);
}

// Find transcript in specific language
Transcript transcript = transcriptList.findTranscript("en");

// Find manually created transcript
Transcript manualyCreatedTranscript = transcriptList.findManualTranscript("en");

// Find automatically generated transcript
Transcript automaticallyGeneratedTranscript = transcriptList.findGeneratedTranscript("en");

Transcript object contains transcript metadata and provides methods for translating the transcript to another language and fetching the actual content of the transcript.

Transcript transcript = transcriptList.findTranscript("en");

// Translate transcript to another language
Transcript translatedTranscript = transcript.translate("de");

// Retrieve transcript content
TranscriptContent transcriptContent = transcript.fetch();

TranscriptContent contains actual transcript content, storing it as a list of Fragment. Each Fragment contains 'text', 'start' and 'duration' attributes. If you try to print the TranscriptContent, you will get the output looking like this:

content=[{text='Text',start=0.0,dur=1.54},{text='Another text',start=1.54,dur=4.16}]

Note: If you want to get transcript content in a different format, refer to Use Formatters.

You can also use getTranscript:

TranscriptContent transcriptContent = youtubeTranscriptApi.getTranscript("videoId", "en");

This is equivalent to:

TranscriptContent transcriptContent = youtubeTranscriptApi.listTranscripts("videoId")
        .findTranscript("en")
        .fetch();

Given that English is the most common language, you can omit the language code, and it will default to English:

// Retrieve transcript content in english
TranscriptContent transcriptContent = youtubeTranscriptApi.listTranscripts("videoId")
        //no language code defaults to english
        .findTranscript()
        .fetch();
// Or
TranscriptContent transcriptContent = youtubeTranscriptApi.getTranscript("videoId");

🔧 Detailed Usage

Use fallback language

In case if desired language is not available, instead of getting an exception you can pass some other languages that will be used as a fallback.

For example:

TranscriptContent transcriptContent = youtubeTranscriptApi.listTranscripts("videoId")
        .findTranscript("de", "en")
        .fetch();

// Or
TranscriptContent transcriptContent = youtubeTranscriptApi.getTranscript("videoId", "de", "en");

It will first look for a transcript in German, and if it doesn't find one, it will then look for one in English, and so on.

Find transcripts

By default, findTranscript will always pick manually created transcripts first and then automatically generated ones. If you want to get only automatically generated or only manually created transcripts, you can use findManualTranscript or findGeneratedTranscript.

// Retrieve manually created transcript
Transcript manualyCreatedTranscript = transcriptList.findManualTranscript("en");

// Retrieve automatically generated transcript
Transcript automaticallyGeneratedTranscript = transcriptList.findGeneratedTranscript("en");

findGeneratedTranscript and findManualTranscript both support fallback languages.

Transcript metadata

Transcript object contains several methods for retrieving transcript metadata:

String videoId = transcript.getVideoId();

String language = transcript.getLanguage();

String languageCode = transcript.getLanguageCode();

// API URL used to fetch transcript content
String apiUrl = transcript.getApiUrl();

// Whether it has been manually created or automatically generated by YouTube
boolean isGenerated = transcript.isGenerated();

// Whether this transcript can be translated or not
boolean isTranslatable = transcript.isTranslatable();

// Set of language codes which represent available translation languages
Set<String> translationLanguages = transcript.getTranslationLanguages();

Use Formatters

By default, if you try to print TranscriptContent it will return the following string representation:

content=[{text='Text',start=0.0,dur=1.54},{text='Another text',start=1.54,dur=4.16}]

Since this default format may not be suitable for all scenarios, you can implement the TranscriptFormatter interface to customize the formatting of the content.

// Create a new custom formatter
Formatter transcriptFormatter = new MyCustomFormatter();

// Format transcript content
String formattedContent = transcriptFormatter.format(transcriptContent);

The library offers several built-in formatters:

• JSONFormatter - Formats content as JSON
• JSONPrettyFormatter - Formats content as pretty-printed JSON
• TextFormatter - Formats content as plain text without timestamps
• WebVTTFormatter - Formats content as WebVTT
• SRTFormatter - Formats content as SRT

These formatters can be accessed from the TranscriptFormatters class:

// Get json formatter
TranscriptFormatter jsonFormatter = TranscriptFormatters.jsonFormatter();

String formattedContent = jsonFormatter.format(transcriptContent);

YoutubeClient customization

By default, YoutubeTranscriptApi uses Java 11 HttpClient for making requests to YouTube, if you want to use a different client, you can create your own YouTube client by implementing the YoutubeClient interface and passing it to the YoutubeTranscriptApiFactory createWithClient method.

// Create a new custom YoutubeClient
YoutubeClient youtubeClient = new MyCustomYoutubeClient();

// Create YoutubeTranscriptApi instance with custom YouTubeClient
YoutubeTranscriptApi youtubeTranscriptApi = TranscriptApiFactory.createWithClient(youtubeClient);

Cookies

Some videos may be age-restricted, requiring authentication to access the transcript. To achieve this, obtain access to the desired video in a browser and download the cookies in Netscape format, storing them as a TXT file. You can use extensions like Get cookies.txt LOCALLY for Chrome or cookies.txt for Firefox to do this. YoutubeTranscriptApi contains listTranscriptsWithCookies and getTranscriptWithCookies which accept a path to the cookies.txt file.

// Retrieve transcript list
TranscriptList transcriptList = youtubeTranscriptApi.listTranscriptsWithCookies("videoId", "path/to/cookies.txt");

// Get transcript content
TranscriptContent transcriptContent = youtubeTranscriptApi.getTranscriptWithCookies("videoId", "path/to/cookies.txt", "en");

🤓 How it works

Within each YouTube video page, there exists JSON data containing all the transcript information, including an undocumented API URL embedded within its HTML. This JSON looks like this:

{
  "captions": {
    "playerCaptionsTracklistRenderer": {
      "captionTracks": [
        {
          "baseUrl": "https://www.youtube.com/api/timedtext?v=dQw4w9WgXcQ&asr_langs=de,en,es,fr,it,ja,ko,nl,pt,ru&caps=asr&xorp=true&hl=de&ip=0.0.0.0&ipbits=0&expire=1570645639&sparams=ip,ipbits,expire,v,asr_langs,caps,xorp&signature=5939E534881E9A14C14BCEDF370DE7A4E5FD4BE0.01ABE3BA9B2BCDEC6C51D6A9D9F898460495F0F2&key=yt8&lang=de",
          "name": {
            "simpleText": "Deutsch"
          },
          "vssId": ".de",
          "languageCode": "de",
          "isTranslatable": true
        },
        {
          "baseUrl": "https://www.youtube.com/api/timedtext?v=dQw4w9WgXcQ&asr_langs=de,en,es,fr,it,ja,ko,nl,pt,ru&caps=asr&xorp=true&hl=de&ip=0.0.0.0&ipbits=0&expire=1570645639&sparams=ip,ipbits,expire,v,asr_langs,caps,xorp&signature=5939E534881E9A14C14BCEDF370DE7A4E5FD4BE0.01ABE3BA9B2BCDEC6C51D6A9D9F898460495F0F2&key=yt8&lang=en",
          "name": {
            "simpleText": "Englisch"
          },
          "vssId": ".en",
          "languageCode": "en",
          "kind": "asr",
          "isTranslatable": true
        }
      ],
      "translationLanguages": [
        {
          "languageCode": "af",
          "languageName": {
            "simpleText": "Afrikaans"
          }
        }
      ]
    }
  }
}

This library works by making a single GET request to the YouTube page of the specified video, extracting the JSON data from the HTML, and parsing it to obtain a list of all available transcripts. To fetch the transcript content, it then sends a GET request to the API URL extracted from the JSON. The YouTube API returns the transcript content in XML format, like this:

<?xml version="1.0" encoding="utf-8" ?>
<transcript>
    <text start="0" dur="1.54">Some text</text>
    <text start="1.54" dur="4.16">Some additional text</text>
</transcript>

📖 License

This library is licensed under the MIT License. See the LICENSE file for more information.