Merge video clips, voiceover, and captions into an MP4 with Apify

Description

Quick overview
Turn 1–10 video clips, an optional voiceover and optional SRT captions into one finished MP4 for YouTube Shorts, Reels or TikTok, without hosting FFmpeg yourself. Built for faceless channels, AI video pipelines and agencies. Runs on Apify at $0.20 per finished video; failed jobs and the demo are free.

How it works
Starts when you run the workflow manually.
Builds a video job payload that includes a list of clip URLs plus optional voiceover and SRT captions, along with orientation, fit mode, and a maximum duration.
Sends the job to the Apify Short Video Assembler API to scale/crop or pad clips, concatenate them, add the voiceover, and burn in captions into a single MP4.
Returns the resulting public MP4 URL along with the render duration and job status.

Setup
Create an Apify account and copy your Apify API token from Apify Console.
In the HTTP request to Apify, add an HTTP Header Auth credential with Authorization: Bearer .
Update the job payload to include 1–10 publicly accessible clips URLs (and optionally voiceover_url and captions_srt) and adjust orientation, fit, and max_seconds as needed.

Requirements
Apify account (free tier works) and its API token
Video clips and audio at public http(s) URLs
Pay per use: $0.20 per finished video on Apify, no subscription

Customization
Set orientation to vertical (1080x1920), horizontal or square, and fit to crop or pad
Limit length with max_seconds (1-60)
Swap the manual trigger for a schedule, form or webhook, and send the video URL to YouTube, Google Drive or Slack

Additional info
Try it before adding your own media: run the workflow once with the empty clips list and it renders a free 12-second demo video. Each output is checked (length, resolution, audio track) before you are charged.