Subtitles as .srt
SubRip's .srt format has outlived nearly every video tool that came after it, and it's still what most players, editors and platforms expect when you say "subtitles." Send audio to this endpoint and get back a properly numbered, correctly timed .srt file — not raw text you still have to format yourself.
Run it online
Run this on our servers with your account. Free tools run in your browser; this one bills your KIT balance per the price above.
Why .srt is still the default
SubRip started life as a tool for ripping subtitle streams off DVDs, and its output format — a plain numbered list of timecoded text blocks — turned out to be simple enough that almost every video player, editor and platform since has kept supporting it rather than replacing it. Decades on, it's still the format a client asks for by name, and the one most upload forms accept without a conversion step.
What the endpoint delivers
POST an audio file to /audio/subtitles-srt and the task transcribes the speech, groups it into readable subtitle lines at natural breakpoints, and assigns each line a start and end timecode in the exact numbering and formatting the .srt spec expects. The output is a file, not a data structure to reassemble — it downloads or attaches to a webhook payload ready to load into a video editor or player as-is.
How line breaks get decided
Good subtitles aren't just a transcript chopped at arbitrary intervals — lines need to break at natural pauses and stay short enough to read comfortably before the next one appears. The task times each line against the actual audio so captions appear and disappear in step with speech, rather than lagging behind or cutting off mid-sentence the way a naive fixed-interval split would.
Where it fits in a video workflow
Most requests come from teams publishing video who need captions fast: a course platform captioning new lessons, a company localizing internal training, a creator adding subtitles to boost watch time and accessibility on a platform that surfaces captioned video more favorably. Because the task runs asynchronously, a batch of episodes can be submitted together and each .srt file lands by webhook as it's ready, or pulled from a signed link on your own schedule.
Pricing and reliability
The cost is a small per-request base fee plus a per-minute rate tied to audio length, the same transparent shape as plain transcription — generating captions doesn't carry a premium beyond the transcription work itself. A failed generation retries automatically up to three times and is never billed if it still can't complete, so a large batch of episodes only costs you for the files that actually land.
What you can do with it
Online course captioning
A course platform generates .srt files for every new lesson upload so students can follow along in a second language or a noisy environment.
YouTube and social video accessibility
A creator captions each upload to improve accessibility and watch time on platforms that favor captioned video in recommendations.
Corporate training localization
A company generates a base .srt from an English training video, then feeds it to a translation step to produce subtitle files for other markets.
Archive footage captioning
A media archive runs old, uncaptioned interview footage through the endpoint to make decades of recordings searchable and accessible.
FAQ
How do I generate an .srt file from audio with this API?
POST an audio file to /audio/subtitles-srt and the task returns a properly formatted, correctly timed .srt subtitle file via webhook or a signed link.
Does the output work directly in video editors and players?
Yes, the file follows the standard .srt numbering and timecode format that editors and players expect, so it loads without any reformatting.
Is the SRT generator API free to use?
There's no free tier — free tiers get abused and slow everyone down. Access runs on a prepaid ForHosting KIT balance: top up from $10.00 (it never expires) and each request is charged at its published price, so a call with no balance returns HTTP 402. No subscription, no tokens, no invented credits, and a failed task is never charged.
How accurate is the line timing?
Each line is timed against the actual audio and broken at natural speech pauses, so captions track what's being said rather than lagging or cutting mid-sentence.
Can I generate subtitles for a whole season of episodes at once?
Yes, each audio file is its own asynchronous request, so a batch of episodes can be submitted together and results collected by webhook as each one finishes.
Do you also support .vtt subtitles?
Yes, the VTT subtitle endpoint produces WebVTT output for HTML5 video from the same kind of audio input.
What languages can it caption?
The endpoint follows the same broad language coverage as standard transcription, with automatic language detection or an explicit language setting.
What happens if subtitle generation fails?
The task retries automatically up to three times before returning a clear error, and a failed request is never charged.
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, and soon from our app, email and Telegram.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/audio/subtitles-srt \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"audio":"https://ejemplo.com/audio.mp3"}'const res = await fetch("https://api.kit.forhosting.com/audio/subtitles-srt", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"audio": "https://ejemplo.com/audio.mp3"
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/audio/subtitles-srt",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"audio": "https://ejemplo.com/audio.mp3"
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/audio/subtitles-srt", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"audio":"https://ejemplo.com/audio.mp3"}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"audio":"https://ejemplo.com/audio.mp3"}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/audio/subtitles-srt", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"audio": "https://ejemplo.com/audio.mp3"
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "audio.subtitles_srt",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Limits
max_mb | 200 |
max_minutes | 180 |
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |
422 | task_failed | The task failed after 3 retries. You are never charged for it. |