LinkedIn Post Image API — Generate Post Images & Article Banners From Any Title

ThumbAPI generates 1200×627 LinkedIn post images and article banners from any title. One REST call returns a production-ready image you can attach to a LinkedIn post or use as the hero of a LinkedIn Article — no design tool, no template, no manual crop.

LinkedIn posts with images get significantly more reach than text-only updates. The bottleneck is making one for every post. ThumbAPI replaces that work with a single HTTP POST: send the title, get back a base64 WebP sized exactly to LinkedIn's in-feed aspect ratio.

curl -X POST https://api.thumbapi.dev/v1/generate \
  -H "x-api-key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "title": "How we cut our cloud bill 40% in one quarter",
    "format": "linkedin",
    "category": "business-finance"
  }'

LinkedIn Image Sizes — Know the Difference

LinkedIn has several image slots with different aspect ratios. Use the wrong one and your image gets cropped or letterboxed:

This page covers in-feed post images and LinkedIn Article banners — both use the same 1200×627 1.91:1 layout. For link cards (when someone shares your URL), use format: "blogpost" and add a standard og:image meta tag (see the OG Image API guide). The profile cover banner (1584×396) is a separate use case and not yet a first-class ThumbAPI format.

How It Works

Three steps. No SDK, no polling — the image is returned inline in the same HTTP response.

1. POST your title with format: "linkedin" and optional flags for category, style, photo, or logo overlay.
2. The layout is selected from the format and a set of title heuristics — the same deterministic pipeline as every other format on ThumbAPI.
3. Receive a 1200×627 base64 imagein the JSON response. Save it to disk, upload via LinkedIn's Assets API, or push it into your scheduling tool.

Three style options match LinkedIn content tone:

• Faceless (default, no flags) — clean typography and graphic design, no people. Best for thought-leadership posts, B2B insights, and case studies.
• Personalized (usePhoto: true) — includes your face or a photo. Pass inline via photoImage (max 2MB) or save a Personal Photo asset and just toggle the flag. Good for personal-brand thought leaders and founder accounts.
• Branded (useLogo: true) — your company logo overlaid on the image. Pass via logoImage (max 1MB) or save a Logo asset. Combine with usePhoto for founder-led brand posts.

Pairing With LinkedIn Category

LinkedIn audiences expect a specific visual tone — usually business/finance, tech/SaaS, or education. The category parameter biases generation toward that niche so your output fits the feed:

• business-finance — earnings, leadership, strategy posts
• tech-saas — product launches, engineering posts, industry analysis
• education-tutorial — how-to threads, courses, professional development
• creative-design — agency portfolios, design case studies

Full category list and behavior is documented at /docs/endpoints/generate.

Posting to LinkedIn Automatically

ThumbAPI returns the image as base64 — decode it and push it to LinkedIn via the official Marketing/Posts API:

1. Generate the image: POST to /v1/generate with format: "linkedin".
2. Decode the base64 from response.image into binary bytes.
3. Register an upload with LinkedIn's Assets API (POST /rest/assets?action=registerUpload) — you get back an upload URL and an asset URN.
4. PUT the binary bytes to the upload URL, then create a UGC post via POST /rest/posts referencing the asset URN.

Prefer no-code? Use Zapier, Make.com, or n8n — every one has an official LinkedIn node that accepts a base64 or binary image and posts it automatically.

Who Uses This

Pricing

Pricing is metered in credits. A standard 1K LinkedIn image costs 10 credits; add-ons (saved photo, saved logo, custom reference set) add +2 each; a 2K (hd) render costs 20 credits instead of 10.

All plans include every format and style. Free-tier output carries a small ThumbAPI watermark — paid plans (Creator and up) return watermark-free images. See full pricing details.

FAQ

What size should LinkedIn post images be?

LinkedIn recommends 1200×627 (1.91:1) for in-feed post images and LinkedIn Article hero banners. ThumbAPI generates exactly this size when you set format: "linkedin".

Is this the same as the LinkedIn cover banner?

No. The personal / company cover banner is 1584×396 (4:1 ratio) and is a separate slot. The LinkedIn Post Image API generates 1200×627 images, which is the size LinkedIn uses for in-feed posts and Article banners.

How is this different from the OG Image API?

OG images are link previews — when someone shares a URL on LinkedIn, the platform pulls og:image and renders it as a 1200×630 card. The LinkedIn Post Image API generates images you attach directly to a LinkedIn post or use as the hero of an Article. Same aspect ratio (1.91:1), different format value (linkedin vs blogpost) and different semantic role.

Can I auto-post the image to LinkedIn?

Yes. Decode the base64 from the response, register an asset via LinkedIn's Assets API, upload the binary, then create a UGC post. About a dozen lines of code, or zero if you go through Zapier, Make.com, or n8n.

Can I add my company logo to the image?

Yes. Set useLogo: true for a logo overlay, usePhoto: true for a personal photo overlay, or both. Save assets once via custom assets, or pass them inline per request.

How long does generation take?

Typical end-to-end latency is 15–25 seconds. The image is returned in the same HTTP response — no polling, no webhook for basic use.