Three things in Thumblify cost 0 credits: title suggestions, the prompt enhancer and browsing the Public Library. Only generating an image draws the balance down — and that is the whole rule, not a summary of one.
The three split cleanly in two. Title suggestions and the prompt enhancer are AI calls that produce text, so they cost nothing but are capped at 40 calls an hour each. The Public Library is just a page: no credits, no rate limit, and no account required to look at it.
What is free, and what limits it
| Tool | Credits | Limit | Account needed |
|---|---|---|---|
| Title suggestions | 0 credits | 40 per hour | Yes |
| Prompt enhancer | 0 credits | 40 per hour | Yes |
| Public Library — browsing | 0 credits | none | No |
The two rate limits are per endpoint and counted per account against a fixed clock hour. They are separate budgets rather than one shared pool, so a heavy run of title suggestions cannot eat the enhancer's allowance. A refusal names the exact time the allowance renews, and nothing is charged either way.
Why these are free and generating is not
Every one of them stops short of an image model.
Title suggestions and the prompt enhancer send text to a text model and get text back. That is cheap enough that metering it in credits would cost more attention than it saves, so it is metered in calls per hour instead — the hourly cap exists to stop a loop, not to ration the feature.
The Public Library is cheaper still: it reads rows that already exist, thumbnails other people chose to make public. It generates nothing, so it has no price.
Generating is the opposite case on every count: it calls an image model, it takes real time, and it produces a file that has to be stored and served. That is what a credit pays for.
How to use them
Title suggestions — on /title-ideas, describe the video and get five titles back per press. Nothing is charged and no image is made. The page states the hourly allowance on itself rather than leaving you to discover it.
The prompt enhancer — in the generator, it rewrites what you typed into a full scene description before the image model sees it. It works on the text, not on a picture. It is also optional in a way worth knowing: every generation is enhanced server-side anyway, so the button is there to let you read and adjust the rewrite, not to unlock it.
The Public Library — /library is open to anyone, signed in or not. Filter by niche, mood, style and model, and click any thumbnail for a closer look. It is the fastest way to see what the models actually produce before spending anything.
What it does not do
Free does not mean unlimited. Title suggestions and the prompt enhancer stop at 40 calls in an hour each. The library has no rate limit because it never reaches a model.
Browsing the library is not a free generation. Looking at a thumbnail in the Public Library costs nothing. Acting on one does: Recreate and Add your face both call an image model and both charge credits, at their own fixed prices.
The prompt enhancer is not a spellchecker for your title. It writes a scene description for the image model. The words you typed are not what reaches the model unless you turn it off.
None of these produces an image. They produce text, or a page of pictures that already exist.
Free tools are not the Free plan. These four cost nothing on every plan including Free — but what the Free plan itself grants you, and what it exports at, is a separate question with its own answer.
Questions people actually ask
How many titles can I generate? 40 calls per hour, five titles a call. The same allowance applies separately to the prompt enhancer.
Do I need an account to browse the Public Library? No. /library is open to anyone. Title suggestions and the prompt enhancer need you signed in, because the hourly allowance is counted per account.
Are these tools restricted by plan? No. All four are the same on Free, Basic, Pro and Elite.
Does re-downloading a thumbnail I already made cost anything? No. The file exists; downloading it again is not a generation.
Does Recreate or Add your face cost credits? Yes, both. They are reached from the Public Library, but they call an image model and are priced accordingly — the price list is here.
What happens when I hit the hourly limit? The request is refused with the time the allowance renews. Nothing is charged either way.
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Verified against the product on 2026-09-01. The source for an article about this product is its own code:
- Title suggestions, no credit reservation —
functions/api/title-ideas.js - Prompt enhancer, no credit reservation —
functions/api/enhance-prompt.js - The hourly allowances, both of them —
RATE_LIMITSinfunctions/lib/rateLimit.js; the one the interface states is mirrored insrc/rateLimits.js(TITLE_IDEAS_PER_HOUR), with a test asserting the two agree - The Public Library, public and unauthenticated —
functions/api/library.js - The only endpoint that reserves credits —
functions/api/generate.js(reserveStatements) - Credit costs that do apply, for contrast —
src/pricing.js(MODEL_CREDIT_COST), and the fixed prices for Recreate and Add your face