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Auto-Caption Videos With n8n and Submagic

Disclosure: CreatorIntelHQ may earn a commission if you buy through some links. This page is based on hands-on testing and documented observations.

⚠️ Can You Get a Watermark-Free Submagic Export for Free?

Yes — through Submagic's API, and this free n8n workflow does it for you. It takes a video URL, sends it to Submagic, waits for the render, and hands back a download link to a captioned file.

We built it and ran it on 22 September 2026, downloaded the output and inspected it frame by frame: 1080×608, 90 seconds, captions burned in, and no watermark anywhere in the file. Submagic's editor refuses to export at all on a free account — this route does not.

The allowance is small but real: 10 API credits a month on the trial, at one credit per minute of video, so roughly two 90-second clips.

Two things will trip you up, and neither is in the documentation: the REST API rejects the Authorization: Bearer header that Submagic's own setup snippet shows, and adding an export step re-renders the project and charges you twice.

→ Get the workflow

By Gaurav Sharma · Last updated October 5, 2026 · Evidence status: Strong

Based on hands-on testing · How we test creator tools

Get the workflow

Get the n8n workflow

The six-node workflow we built and ran on 22 September 2026, exported from n8n and ready to import. Includes the two fixes that are not in Submagic's documentation.



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The workflow is free. Tell us where to send it and the file comes straight back — then in n8n: Workflow menu (…) → Import → From file.

What it does

Six nodes, one job:

  1. Configure — you set the video URL, a title, and the language
  2. Create project — POST https://api.submagic.co/v1/projects
  3. Wait 30s
  4. Check status — GET https://api.submagic.co/v1/projects/{id}
  5. Render finished? — if status is completed, continue; otherwise loop back to the wait
  6. Captioned video ready — outputs downloadUrl, directUrl and projectId

The loop matters. Our 90-second clip took about three minutes end to end, and it polled twice before the render was ready. A fixed delay works until the day you feed it a longer video, then it fails silently.

We ran this exact template again on 4 October 2026, this time on self-hosted n8n: 66.6 seconds end to end. Sixty of those seconds were the two wait steps; n8n's own work — creating the project and two status checks — took about 6.5 seconds. The render time is Submagic's, not n8n's.

The same workflow, run on self-hosted n8n: every step time read from the n8n execution log.

Setup

You need: an n8n instance (Cloud's trial is fine), a Submagic account, and a publicly reachable URL for the video you want captioned.

Want your own n8n instead of Cloud? We deployed n8n with a Postgres database on Railway from the command line: about 40 seconds from the deploy command to a working instance. Railway bills for what the services use, around the clock — idle, our n8n held about 632 MB of memory and Postgres 144 MB.

Deploy n8n on Railway

Affiliate link: we may earn a commission if you sign up and pay. Railway says referred sign-ups get $20 in credits.

The Railway deploy, replayed from our real terminal log.

No Submagic account yet? The trial issues an API key immediately, with no card and no upgrade step — that is the account this whole guide was tested on. You need your own key: workflow templates never carry anyone else's credentials.

Get a free Submagic API key

  1. Import the workflow.
  2. Open Create project, and under Header Auth choose Create new credential.
  3. Set Name to x-api-key and Value to your Submagic API key — generate one at API & Integrations in the Submagic dashboard. Save.
  4. Open Check status and select the same credential from the dropdown. It does not inherit, and this is the single most likely reason your first run fails.
  5. Put your video URL in the Configure node and run it.

The auth gotcha

Submagic's dashboard hands you a setup snippet using Authorization: Bearer <key>. That header works on their MCP endpoint. On the REST API it returns UNAUTHORIZED. The REST API wants x-api-key.

We only found this by trying both. If you build against the documentation you will get a 401 with nothing to tell you why, which is exactly the kind of wall that makes people give up on an API that actually works fine.

What it actually costs

Submagic meters API use separately from the credits you see in the app — a detail worth knowing, because watching the wrong counter tells you nothing. Their API & Integrations page states the rule plainly:

Each minute of video processing consumes 1 credit. Upon exceeding this limit, your API access will be suspended until the next month.

On the trial that is 10 credits a month. Our 90-second clip cost 2 — ninety seconds rounds up to two minutes. So the practical ceiling is about two clips of that length per month, or ten minutes of video however you slice it.

The dashboard credit balance in the main app does not move when you run this. It is a different ledger. We watched it sit unchanged at 12 through a render that definitely happened.

⚠️ Do not add an export node. Submagic's POST /projects renders automatically once transcription finishes. Calling the export endpoint afterwards re-renders a project that is already done and charges you for it twice. Just poll GET /projects/{id} until downloadUrl appears, which is what the workflow does.

The part that surprised us

On a Submagic trial account, the web editor will not let you export at all. Click Export and you get a modal reading "Your video's ready — upgrade to export," which loops into a referral offer and back again with no path to a file.

The API, on the same account, on the same day, rendered the clip and returned a working download link. Afterwards the editor showed that project badged "Exported" and offered Download and Publish — the same buttons it had refused minutes earlier on the project beside it.

We documented that in full, with screenshots, in does Submagic add a watermark. It is worth reading before you build anything that depends on this, because a vendor whose two surfaces disagree about your entitlements may change one of them.

Is the output watermarked?

No. We downloaded the file this workflow produced and checked.

Four corner crops from the captioned video produced by the n8n workflow, at full resolution, showing no Submagic logo or wordmark in any corner

All four corners of the workflow's output, cropped at full resolution rather than scaled down. No Submagic logo, wordmark or bug. The visible text is the burned-in caption; the NASA branding came with our public-domain test footage.

The file itself: 16MB, 1080×608, 90.0 seconds, H.264 video with AAC audio. Captions are composited into the frames, which is what you want — they travel with the file wherever you upload it.

Limits worth knowing before you build on this

  • The video URL must be publicly reachable. Google Drive sharing links work. YouTube URLs do not — those need a different Submagic endpoint entirely.
  • Ten minutes a month is a real ceiling. This is enough to prove a pipeline works. It is not enough to run a posting schedule on. If you outgrow it, Submagic's paid plans start at $19/month billed monthly on Starter, and nothing in this workflow changes — the allowance is simply larger.

See Submagic plans

- **The 10-credit allowance is issued at signup.** We confirmed it on a second, separate trial account on 24 September 2026 — 10 API minutes, unused, before an API key existed. Submagic lists it as its own meter in **My Account › Profile** (`API Minutes 0/10`), separate from the editor's credits. What we have **not** watched happen is a renewal: our first account's balance has not moved in a month, so "per month" is Submagic's stated rule, not something we have observed firing. - **Free tiers move.** Submagic changed its free plan twice during 2026 — from per-feature counters to a credit pool, and from a watermarked export to no export at all. Anything built on a free allowance is worth re-checking before you depend on it.

FAQ

Do I need to pay for Submagic to use this?

No. The trial includes API access with its own 10-credit monthly allowance, which is what we tested on. You will need your own account and your own API key — workflow templates never carry someone else's credentials.

Why doesn't the Bearer token work?

Submagic runs two surfaces. The MCP endpoint takes Authorization: Bearer; the REST API that n8n calls takes x-api-key. The setup snippet in the dashboard shows the MCP form, which is what makes this confusing.

How long does a render take?

About three minutes for a 90-second clip, including download and transcription. The workflow polls every 30 seconds, so it adapts to longer videos on its own.

Not with this workflow. Submagic handles YouTube through a separate Magic Clips endpoint that splits a long video into several short ones — a different job with a different output.

Will this work on a paid Submagic plan?

Yes. Nothing here depends on the trial; the allowance is simply larger. The free tier is how we tested it, not a requirement.