Knowledge Base
Frequently asked questions
Details on credit packs, model behavior, image resolution, and account access.
How does Thumbly preserve the subject from my photo?▼
We send your uploaded image as an input reference to a multimodal image generation endpoint. The model extracts facial contours and lighting cues from the photo, then renders the selected aesthetic around your subject instead of generating a generic face.
Do purchased credits expire?▼
No. Credits remain in your account balance until you use them. There are no monthly resets and no subscriptions.
What aspect ratio and resolution are generated?▼
Every generation is rendered at native 16:9 aspect ratio. YouTube displays thumbnails at 1280x720, and our output matches this aspect ratio so no cropping is necessary.
What happens if a generation fails?▼
Our backend runs transactions on Convex. If the generation call to the upstream provider fails, the deducted credit is automatically refunded to your balance.
Can I use generated thumbnails on monetized YouTube channels?▼
Yes. You have full permission to use generated images on monetized videos, sponsored content, and promotional materials.
What file formats can I upload as a reference?▼
Thumbly accepts PNG, JPEG, and WEBP images. Clear portrait or waist-up photos with balanced lighting work best.
Can I write my own prompt instead of using the presets?▼
Yes. You can select any preset and add custom prompt text (such as props or specific backgrounds), or provide a completely custom prompt.
How do I get the 100 free credits?▼
New accounts receive 100 welcome credits upon signup. During the current private beta, sign-in is enabled via early access invitations.
Need more help?
If your question is not listed here, email us directly at hello@thumbly.app.