Tech channels on YouTube have a specific thumbnail problem. The subject is usually a rectangle that glows: a laptop, a phone, a terminal, a dashboard. Rectangles are hard to make interesting, and the version of the shot you took at your desk is almost never the version that reads at the size it actually appears in a sidebar.
WThumb works from a reference rather than from an idea. You pick the frame first (16:9 for YouTube, 9:16 for Shorts), then paste a YouTube link or upload an image so there is a layout to rebuild. Optionally you add one clear photo of yourself. Then you write the words for the thumbnail in one field, and everything else you want changed in the other field, in plain sentences. That second field is where the prompt ideas below go.
Each of the twelve is written to be pasted as-is. Change the brand names, the colors and the objects to match your video, and leave the structure alone: name the thing, say where it goes, say what it should look like. One run produces one image and takes about thirty seconds. There is no editor afterwards, so if something lands wrong you describe the fix in a revision or run it again.
The tech thumbnail maker is the focused starting point for software, AI tool, review, build, and workflow videos, with real WThumb examples in face-led and faceless formats.
How to write a request the tool can act on
Two fields do different jobs, and mixing them up is an easy way to waste a run. "The words on it" is the literal text that gets rendered on the thumbnail, up to three lines. "Anything else" is a description of changes: colors, clothing, backgrounds, logos, objects, what to remove.
A line typed in CAPITALS is treated as literal text to render. A sentence like "write BROKEN instead of dead" is read as an instruction about the text, not as a thing to paste on the image. One word on its own is always treated as literal. Worth knowing before you type a brand name in capitals and wonder why it appeared across the frame.
You can attach up to four extra images alongside your request and point at them with @1, @2 and so on. That is how a real product shot, a real logo or a real screenshot gets into the thumbnail rather than an approximation of one. Uploads are PNG, JPEG or WebP; photos up to 8 MiB, references up to 12 MiB.
- Name the object. "The laptop screen" beats "the device in the middle."
- Give it a position. Left, right, lower corner, behind the shoulder, in the hand.
- Say what stays. If the background is already right, say to keep it. Otherwise it is fair game.
- One change per sentence. Four short sentences read better than one long one held together by commas.
Tech thumbnail prompts for logos, screens and products
The first four cover the most common tech thumbnail shapes: a brand mark, a glowing display, something held up to the camera, and a comparison.
1. Swap the logo on the screen
Use this when the reference has the right composition but the wrong brand on it, which is normal when the video you are using as the reference is about a different tool.
Paste: "Replace the logo on the laptop screen with the Notion logo, same size and same position. Keep the glow coming off the screen."
2. Make the screen glow carry the frame
When the subject is a monitor or a phone, the light coming off it is what separates the shot from a product photo. Push it harder than looks natural at full size; at sidebar size it reads as normal.
Paste: "Make the monitor screen much brighter with a strong blue glow spilling onto the desk and onto the face and shoulders. Darken the rest of the room so the screen is the brightest thing in the frame."
3. Product in hand, held toward the camera
For reviews and unboxings. The gesture reads at a glance even when the object itself is unrecognisable at small size, which most objects are.
Paste: "Put a black smartphone in the right hand, held up toward the camera at chest height, screen facing the viewer and lit up. Keep the pose and the background as they are."
4. Before and after split
For migrations, refactors, redesigns and speed comparisons. The split does the explaining, so the text does not have to.
Paste: "Split the frame down the middle with a thin white vertical line. Left side is a cluttered messy code editor in dull gray tones. Right side is a clean minimal code editor in bright green tones. Keep the person centered over the line."
Tech thumbnail prompts for color, mood and attention
The next four are about where the eye lands. Tech thumbnails go gray easily. One saturated color used deliberately does more than five used politely.
5. Force a single accent color
Use this when the reference is well composed but tonally flat, or when you want a consistent palette across a series and have nothing enforcing it.
Paste: "Change the background to deep navy, almost black. Make every accent in the frame bright orange: the arrow, the badge outline and the glow on the keyboard. Nothing else should be colored."
6. Add a real product shot with @1
Worth doing whenever you have the real asset to hand. If you attach the actual box, board or screenshot as image 1, you get the real thing in the frame instead of a plausible-looking invention of it.
Paste, with the product photo attached as image 1: "Put @1 in the lower right corner at about a quarter of the frame width, slightly angled, with a soft shadow underneath so it sits on the surface. Do not crop it."
7. Ask for a different expression
Your photo takes the pose, framing and lighting of the person in the reference, so the face you get is shaped by the reference as much as by the sentence you write. Ask for the change in one word and hold everything else still. Then look at the result before deciding it worked: if the expression has not moved far enough, a reference whose person already has the look you want will get you there faster than another sentence will.
Paste: "Change the expression to surprised, eyebrows raised and mouth slightly open, still looking straight at the camera. Keep the same haircut, clothing and lighting."
8. Heavier text with a hard outline
Text on a busy screenshot disappears. An outline or a solid block behind it is what keeps it readable when the thumbnail is the size of a postage stamp on a phone. The words themselves belong in "the words on it"; how they look is described here, in the same plain sentences as everything else. Of the twelve, this is the one to check most closely on the result, since weight, outline and position are all being asked for at once.
Paste: "Make the text much heavier, in a bold condensed sans-serif, with a thick black outline and a soft drop shadow. Move it to the top left so it does not sit over the face."
Prompts for restraint and for making the device the subject
The last four are subtractive or structural. They tend to be the ones that actually rescue a thumbnail, because most failing thumbnails have too much in them rather than too little.
9. Remove the clutter
Desk shots collect junk: cables, mugs, a second monitor, a stack of paper. None of it survives being shrunk. Name the items rather than asking for a general tidy-up.
Paste: "Remove the coffee mug, the cables and the papers from the desk. Leave the desk surface empty and clean. Keep the laptop and the person exactly where they are."
10. Make the device the subject
For hardware videos where the object, not you, is the reason someone clicks. Scale is the instruction that matters here, not detail.
Paste: "Make the laptop much larger so it fills the left two thirds of the frame, angled toward the viewer. Shrink the person and move them to the right edge, from the shoulders up."
11. Cold or warm grading
Grading is a fast way to signal genre. Cold blue reads technical, serious, benchmark-and-teardown. Warm orange reads tutorial, opinion, human. Pick one and commit, because a thumbnail that is slightly both looks like it was not graded at all.
Cold: "Grade the whole image cold. Blue and cyan tones throughout, slightly desaturated skin, deep shadows, one small warm highlight on the keyboard."
Warm: "Grade the whole image warm. Orange and amber tones, warm light coming from the left, softer shadows, background slightly out of focus."
12. The faceless variant
If you skip the photo step entirely, the person in the reference is removed and the space they occupied is filled with supporting graphics in that reference's own style. Then you use "anything else" to say what belongs in the gap.
Paste, with no photo uploaded: "No person in the frame. Fill the space where they were with a large terminal window showing green text, a red downward arrow beside it, and a small warning badge in the top right."
Running these without wasting attempts
New accounts get two free credits (1 credit = 1 thumbnail), no card required, and they do not renew. That is not many, so treat the first one as a real attempt rather than a test. Pick the reference carefully before you write anything.
The reference sets the starting composition. A layout that was weak to begin with leaves more of the work to the description.
A horizontal reference can be rebuilt into a vertical frame and the other way round. The layout is re-staged rather than cropped, so a 16:9 thumbnail you like can become the basis for a Shorts cover without the sides falling off. Choose the output frame first, then supply the reference.
When a run comes back wrong, resist rewriting the whole request. Change the one sentence that describes the thing that failed, leave the rest identical, and run again. Rewriting everything changes several variables at once and you lose track of which instruction was doing the work.
Paid plans are on the pricing page. New accounts start with two free credits.
