Thumbn

Free plan APIWeb

What Thumbn is

Thumbn creates thumbnail images by examining video scenes, selecting a moment, writing a concept, and rendering images for video platforms. Users can paste a YouTube, TikTok, or Reels link, or upload an MP4 up to 200MB. One concept can produce a 1280×720 YouTube image and a 1080×1920 image for TikTok and Instagram Reels. Users can direct edits to a selected thumbnail, keep every version, and attach a face, logo, or desired look as a reference. Thumbn scores each render against a selected style rubric and re-edits it until it clears the bar. It offers a web app, HTTP API, and MCP server, with Claude, Codex, and Cursor listed as clients. Pro costs $19 a month; Studio costs $49 a month. API and MCP creation use the same subscription credits. Thumbn says customer videos and thumbnails are not used to train its models, sold, or used for advertising.

Who it suits

It suits creators making thumbnails for YouTube, TikTok, Instagram Reels, YouTube Shorts, or podcast cover art who want scene-based concepts and editable versions. API and MCP users need a subscription.

What it does well

Accepts links or MP4 uploads
Produces platform-sized images
Keeps thumbnail versions
Supports reference images
HTTP API and MCP server

What to know first

No free plan
MP4 uploads limited to 200MB
Subscriptions start at $19 a month
No brand kit

Plans

Plan	Billed and limits	Price
Free preview	one watermarked cover per day without an account · free account removes watermark and allows actual Reel uploads, variants and chat refinement	Free
Pro	monthly · 60 credits/month · both image models · no watermark · 4 concepts/run · full agent studio	$19 a month
Studio	monthly · 175 credits/month · everything in Pro · highest monthly allowance · non-expiring credit packs · priority rendering	$49 a month

As thumbn.so lists them, read 15 Oct 2026. The maker's own page has the final word.

Verdict

Thumbn combines automated thumbnail concepts, rendering, scoring, and revisions with web and developer access. The Pro and Studio plans determine credits and features, while API and MCP use the same paid balance.

Facts from Thumbn's own pages

Account requirement: Sign-in uses a Google account rather than a separate Thumbn password. · thumbn.so, 15 Oct 2026
Account security: Thumbn says user API keys are encrypted at rest and are not shown in the browser after saving. · thumbn.so, 8 Oct 2026
API billing: API, MCP and web generations share the same subscription and credit balance, with no separate free API tier. · thumbn.so, 15 Oct 2026
API tools: Documented tools include create_thumbnail, get_thumbnail_job, list_thumbnail_jobs, list_image_models, estimate_cost and get_account. · thumbn.so, 15 Oct 2026
App-store availability: No iOS, Android or Microsoft Store application listing or rating is stated on the opened Thumbn pages; the product is presented as a web service. · thumbn.so, 15 Oct 2026
Authentication: API requests use an x-api-key or bearer token, while MCP uses OAuth 2.1 with authorization-code PKCE and refresh tokens. · thumbn.so, 15 Oct 2026
Automatic grading: Each render is scored against a style rubric and re-edited until it clears the stated threshold. · thumbn.so, 15 Oct 2026
Availability limitation: The terms provide no uptime guarantee and warn that failures or policy changes at third-party AI providers can disable parts of the service. · thumbn.so, 15 Oct 2026
Bring your own keys: Renders using a user's Google, OpenAI, or Anthropic key bill to that provider account instead of using Thumbn credits. · thumbn.so, 8 Oct 2026
Cancellation: Subscriptions can be cancelled from the account billing page at any time, with access continuing through the paid period. · thumbn.so, 8 Oct 2026
Cancellation and refunds: Subscriptions can be cancelled from the billing page; unused prepaid periods are not prorated, and refunds are offered within 14 days only when no generation has been made unless the service caused the problem. · thumbn.so, 15 Oct 2026
Chrome Web Store availability: The opened Chrome Web Store help page explains the store generally, but no Thumbn extension or rating is shown there. · support.google.com, 15 Oct 2026
Conversational editing: Users can select a generated thumbnail and describe edits such as larger text, a different background or an arrow in plain language. · thumbn.so, 15 Oct 2026
Credit calculation: Video analysis costs 2 credits per job; rendered images cost model-specific rates such as 1 credit for Nano Banana Pro and 2 for GPT Image 2. · thumbn.so, 15 Oct 2026
Cross-platform rendering: One run can produce both a 16:9 YouTube image and a 9:16 image for TikTok and Instagram Reels. · thumbn.so, 15 Oct 2026
Data deletion: After account closure, projects, uploads and generated images are stated to be deleted within 30 days, while invoices are retained for six years for tax purposes. · thumbn.so, 15 Oct 2026
Editing: Users can direct edits to a selected thumbnail, and each version is kept rather than overwriting the previous one. · thumbn.so, 8 Oct 2026
Export: Generated versions are downloadable as PNG files. · thumbn.so, 15 Oct 2026
Independent discussion: A LinkedIn post associated with Thumbn emphasizes matching thumbnail concepts to video type and warns that misleading thumbnails can hurt viewer retention and trust. · linkedin.com, 15 Oct 2026
Independent discussion: design guidance: The same LinkedIn page recommends one dominant subject, strong contrast, a single emotional moment and alignment between title and thumbnail. · linkedin.com, 15 Oct 2026
Integrations: Thumbn supports bringing Google, OpenAI or Anthropic API keys for rendering billed directly by those providers. · thumbn.so, 15 Oct 2026
Maker location: The terms say the service is operated from the United Kingdom and provide no registered legal name on the page. · thumbn.so, 15 Oct 2026
MCP clients: The developer page documents connections for Claude, Codex, Cursor and other Streamable HTTP MCP clients. · thumbn.so, 15 Oct 2026
MCP server: Thumbn provides a Streamable HTTP MCP endpoint at https://api.thumbn.so/mcp. · thumbn.so, 15 Oct 2026

Where Thumbn stands on Freedom251

AI Thumbnail Generators#5 of 29
Video Thumbnail Makers#23 of 46