Automate Instagram Reels: One Template, One Row per Post

Automating Reels means locking one format and feeding it rows. Keep a line per post in a spreadsheet, send one API request per line, and a week of Reels renders in about a minute. Each 28-second Reel costs half a credit, so an account that posts daily runs on 15 credits a month.

The finished video

This guide renders Beauty Before & After Reveal - a 28-second 9:16 Reel built around one moment: a magenta seam travels across a locked frame and peels the finished result off the before photo. Five scenes carry it - the client in the chair, the wipe, the full-bleed reveal, a service card, and a booking close.

Eight fields change per post. Watch the output on the template page before you write a single row.

What you need

• A Renderly API key. Create one in the dashboard under Settings → API keys.
• A spreadsheet with one row per post.
• Two photographs per Reel, at URLs that serve the file directly: the before and the after.

Step 1 - Pick the one Reel format you repeat

An account is a format, not a pile of videos. The fourth Reel a follower sees should be recognisable before the caption finishes loading, and that recognition is the only compounding asset in the whole exercise.

So pick one template and stop editing it. Renderly ships more than twenty social templates - a before and after, a service menu, a class schedule, a booking window, a package card. Choose the one that matches the thing you already do every week. From here you are not designing, you are writing rows.

Step 2 - Keep one row per post in the week's log

The queue is not a content calendar to be invented. It is the work you already did:

salon_name and booking_line are the same on every row, so write them once and fill down. The other six change per post, which means a week of Reels is about ten minutes of typing and two photographs a client.

Step 3 - Write the two photographs so the seam lands

photo_after is one field, and the template spends it in 46 overlays: three real appearances, plus 43 single-frame slices between frames 165 and 207 that are the seam wipe itself. One URL fills all of them.

That is why the reveal only works when both photographs are shot from the same distance and angle. A different crop between before and after reads as two videos cut together rather than one thing changing. photo_before is used twice - full-bleed on the opener, then again as the left half of the split.

Step 4 - Check the type against the Instagram chrome

Two fields sit in fixed boxes at display sizes, so they wrap where you tell them to and nowhere else:

{
  "service_name": "Lived-In\nBalayage",
  "service_note": "Four hours, three lifts and one\nclear gloss, cut dry, finished\nwith a soft bevel."
}

service_name gets a 326px box on the opener and a 417px box on the reveal, which is two lines of display type. A third line clips.

Then check the frame itself. booking_line sits 1,237px down a 1,920px frame, mid-frame and clear of everything. credit_line sits at 1,756px, inside the band Instagram's caption and username row covers, so treat it as a signature rather than as information. And the very first frame is a bare photograph, because salon_name only arrives at frame 5 - set the cover frame a beat in rather than letting Instagram grab frame 0.

Step 5 - Render one row per post

One row becomes one POST:

curl -X POST https://renderly.video/api/v1/renders \
  -H "Authorization: Bearer $RENDERLY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "templateId": "beauty-before-after-reveal",
    "replacements": {
      "photo_before": "https://cdn.example.com/mar-before.jpg",
      "photo_after": "https://cdn.example.com/mar-after.jpg",
      "service_name": "Lived-In\nBalayage",
      "stylist_name": "Nadia Farrell",
      "salon_name": "Maison Vermeil",
      "service_note": "Four hours, three lifts and one\nclear gloss, cut dry.",
      "booking_line": "maisonvermeil.com · 020 7946 0912",
      "credit_line": "Nadia Farrell · Lived-In Balayage"
    },
    "webhookUrl": "https://your-app.com/hooks/renderly"
  }'

Any field you leave out keeps the template's default, so a row with a missing photograph still renders and still costs half a credit. Check the sheet before the run rather than the finished Reels.

The request returns a job ID immediately, because rendering is asynchronous. To loop the rows, the Google Sheets guide has it as an Apps Script and the CSV guide has it as a resumable script for a file on disk.

Step 6 - Collect the finished Reels and schedule the posts

Because webhookUrl was included, Renderly posts back per job:

{
  "event": "render.completed",
  "data": {
    "jobId": "cm9x2k4p10001qw8r7a3b2c1d",
    "status": "COMPLETED",
    "outputUrl": "https://cdn.renderly.video/renders/cm9x2k4p10001qw8r7a3b2c1d.mp4",
    "creditsUsed": 0.5,
    "durationInFrames": 840,
    "width": 1080,
    "height": 1920,
    "fps": 30
  },
  "timestamp": "2026-08-24T09:12:44.110Z"
}

Write outputUrl back to the row. Publishing is a separate job - the Instagram Graph API takes a hosted video URL and a caption - and separating the two is the point: render the week on Monday, release one a day.

Payloads are signed with HMAC-SHA256. Verify the signature before you trust the body; the webhooks guide covers the check.

What this costs at scale

Renderly bills 1 credit per minute of 1080p output, rounded up to the nearest half credit. This Reel runs 28 seconds, so each post costs half a credit.

The row worth sitting with is the third. Twenty client accounts posting three times a week use 40% of the cheapest paid plan, which puts the cost of an agency's Reels output somewhere other than the rendering.

Where to go next

The queue is the work, and it lives in a spreadsheet. Wire it up with the Google Sheets guide, or read the faceless Shorts guide for the opposite case, where the content is written in a batch rather than logged as it happens.

If the Reels in question are paid rather than organic, the variant matrix is a different problem with a different answer: batch-rendering ad variants measures it.