How to scrape YouTube Comment Replies with Kotlin

Replies to one YouTube comment. This tutorial gets it with a short Kotlin program and the YouTube Comment Replies API. Each successful call costs 1 credit; errors and not-found answers are free.

1. Get an API key

Sign in to get a key and 100 free credits, no card. Then put the key in an environment variable so it stays out of your code:

export SCRAPEIO_API_KEY="your_key_here"

2. Set up Kotlin

Kotlin on JVM 11 or newer

3. Write the code

Save this as Scrape.kt. Replace YOUR_COMMENT_ID with a real comment_id.

import java.net.URI
import java.net.URLEncoder
import java.net.http.HttpClient
import java.net.http.HttpRequest
import java.net.http.HttpResponse

fun main() {
    val params = mapOf("comment_id" to "YOUR_COMMENT_ID")
    val query = params.entries.joinToString("&") { "${it.key}=${URLEncoder.encode(it.value, Charsets.UTF_8)}" }
    val req = HttpRequest.newBuilder()
        .uri(URI.create("https://scrapeio.com/v1/youtube/video/comment/replies?" + query))
        .header("x-api-key", System.getenv("SCRAPEIO_API_KEY"))
        .build()
    val res = HttpClient.newHttpClient().send(req, HttpResponse.BodyHandlers.ofString())
    check(res.statusCode() == 200) { "HTTP ${res.statusCode()}" }
    println(res.body())
}

This prints the first page. To get the next one, send the value of data.cursor as the cursor parameter and call again until data.has_more is false.

4. Run it

kotlinc Scrape.kt -include-runtime -d scrape.jar && java -jar scrape.jar

The response has the same envelope on every endpoint: success, cached, credits_used, credits_remaining and data. Shared fields such as handle, followers, plays, likes and created_at have the same names on every platform.

Parameters

Name	Type	Description
`comment_id` (required)	string	Comment id from the comments endpoint.
`cursor`	string	Cursor from the previous page's data.cursor.

Errors and what you pay

Status	Meaning	Charged
`200`	Success	Yes, unless cached
`400`	A parameter is missing or wrong	No
`401`	The key is missing or invalid	No
`402`	Not enough credits	No
`403`	The account or post is private	No
`404`	Not found on the platform	No
`429`	More than 300 requests a minute	No
`502`	Every source is down; retry shortly	No

Same endpoint in other languages

Python · Node.js · JavaScript · TypeScript · Go · Rust · Java · C# · PHP · Ruby · Swift · R

Prefer no code?

Connect the MCP server to Claude Code, Cursor or Codex and ask in plain English. The agent uses the youtube_comment_replies tool for you.

100 free credits, no card. Credits never expire.

Get API key