✦ Free OG image checker
OG image checker: see your link preview before you share it
Paste any URL to see how it unfurls in iMessage, X, Facebook, LinkedIn, Slack, Discord, WhatsApp, Bluesky, Mastodon and Google. The checker reads the page’s Open Graph and Twitter tags, measures the share image and video, and tells you what to fix.
01 · What it checks
Eight things every link preview needs
Each app builds its card from a handful of tags in the page’s head. These are the ones that decide whether a link looks finished or broken.
og:title
The headline on the card. Most apps cut it around 60 to 70 characters, so put the important words first.
og:description
One or two sentences under the title. Some apps hide it on phones, so the title has to work on its own.
og:image
The picture that earns the tap. The checker loads it, reads its real size and weight, and flags formats apps can’t show.
Image size and shape
Large cards are about 1.91:1. A 1200x630 image is sharp on phones and fits Facebook, LinkedIn, X and Messages.
og:url and canonical
The address apps file shares under. When it disagrees with the canonical tag, shares and search count two different pages.
twitter:card
Tells X which card to draw. summary_large_image gives the big image. summary gives a small square.
og:video
A short MP4 that Messages and Discord can play in the bubble. The checker tests the file type, byte ranges, size and fast start.
Favicon
The small site icon next to the link in Messages, Slack and Google results.
02 · OG image size by app
What size each app wants
One 1200x630 image covers almost every app. Here is what each one does with it.
iMessage
1200x630
Plays og:video in the bubble. Apple’s budget is 10 MB for icon, image and video together.
1200x630
Ignores images under 200x200. Caches hard, so refetch in the Sharing Debugger after a change.
X
1200x628
summary_large_image wants 2:1, at least 300x157, under 5 MB. JPG, PNG, WebP or GIF.
1200x627
Uses og: tags only. Post Inspector refetches a page on demand.
Slack
1200x630
Shows the site name, title, description and image. Reads og: and twitter: tags.
Discord
1200x630
Colors the embed with theme-color. Plays og:video when og:type is video.other.
1200x630
Uses the same og:image. Keep the file light so it loads before the preview gives up.
Bluesky and Mastodon
1200x630
Show a large image card. Each Mastodon server fetches the page on its own.
03 · Fix a preview
Fix a link preview in four steps
Most broken previews come down to a missing tag, an image apps can’t load, or an old copy sitting in a cache.
1. Run the page through the checker
Fix every red item first. A missing og:image, or one that won’t load, leaves most apps with a bare link.
2. Make a 1200x630 share image
Use a JPG or PNG under 1 MB. Keep text away from the edges, because small cards crop it to a square.
3. Give a new image a new file name
Apps cache images by URL. Replace the file but keep the name, and many apps keep showing the old one.
4. Ask the apps to fetch it again
Facebook’s Sharing Debugger and LinkedIn’s Post Inspector refetch on demand. In Messages, test by sending the link in a new message.
04 · Tags by app
Which tags each app reads
Every app starts from the same Open Graph tags, then adds a few of its own.
iMessage
Draws a large card from the image and title, with the site icon. Plays og:video in the bubble.
og:title · og:image · og:video
X
Reads twitter: tags first and falls back to og: tags. twitter:card picks the large or small layout.
twitter:card · twitter:title · twitter:image
Reads og: tags, and LinkedIn does the same. Both cache hard, so use their debug tools after a change.
og:title · og:description · og:image · og:url
Slack
Shows the site name above the title, then the description and image.
og:site_name · og:title · og:image
Discord
Shows an embed with a colored bar. Plays og:video when og:type is video.other.
og:type · og:video · theme-color
05 · OG image questions
OG image questions, answered
Short answers to common questions about link previews and this checker.
What is an OG image?
It’s the image set by the og:image tag in a page’s head. Messages, Facebook, LinkedIn, Slack and most other apps show it when someone shares the link. OG stands for Open Graph, the tag format Facebook introduced in 2010.
What size should an OG image be?
1200x630 pixels, a 1.91:1 shape. It’s sharp on phones and fits the large cards on Facebook, LinkedIn, X and Messages. Save it as a JPG or PNG under 1 MB.
Why isn’t my link preview updating?
Apps cache previews. Give a new image a new file name, then refetch with Facebook’s Sharing Debugger or LinkedIn’s Post Inspector. This checker keeps a result for 10 minutes. Press refresh on the result to fetch the page again.
Why does my link show no image?
Usually the og:image tag is missing, the URL isn’t a full https:// address, or the server blocks bots. The checker loads the image the way an app would and shows the error it hit.
Can a link preview play video?
In iMessage and Discord, yes. Add an og:video tag that points at a short MP4. Messages needs a server that answers byte-range requests and a total under 10 MB. Other apps show the og:image instead.
What’s the difference between og: and twitter: tags?
og: tags are the Open Graph standard most apps read. X looks for twitter: tags first and falls back to og: tags, so most pages only need twitter:card on top of their og: tags.
Does an OG image help SEO?
Not directly. Google doesn’t rank pages by their share image. A good preview gets more people to tap a shared link, and the title and meta description in the Google preview do matter.
How close is the iMessage preview?
It’s a close copy of how Messages draws a link on iPhone, built from the same tags. Fonts and spacing can differ a little from your phone.
Does the checker keep the pages I check?
It doesn’t keep a history. A result is cached for 10 minutes so repeat checks are fast, then it’s gone.
Is this OG image checker free?
Yes. It’s free, there’s no sign-up, and it works on your phone.
✦ Previews still look wrong?
Let’s make your links worth tapping
I design share images and animated previews that play in Messages, and fix the tags behind them. See it on every page of this site.
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