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Checked on October 26, 2026

CometAPI alternative: Rendergrid

CometAPI is a gateway with one key and one balance for more than 500 models. Below is what the model pages say about our models: in some places amounts per image, in others only per-token rates.

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A Rendergrid article. We’re one of the parties in this comparison, so the CometAPI figures come only from its public pages, each with a link and a date, and below we say separately when CometAPI is the better choice. How we check and correct

01Who it is

What CometAPI is

Briefly, and only from their own pages. Website: cometapi.com.

CometAPI (cometapi.com) is a gateway to 500+ models: text, image, video, and music. For images there are a Gemini-compatible address (/v1beta/models/{model}:generateContent) and an OpenAI-compatible one (/v1/images/generations). The balance is topped up by card through Stripe, 1,000 credits = $1.

Prices on the model pages are shown in different ways: for Nano Banana Pro and Nano Banana 2, approximate amounts per image by resolution (with the “≈” sign); for Nano Banana 2.1 and the GPT Image models, per-token rates. The pricing guide says that for models with an official API the price is 0.8 of the official one.

02Pricing

Prices for our models

How much one image costs at CometAPI and at Rendergrid. The CometAPI prices are from its public pages, checked on .

Comparable cells: 6. Cheaper with us: 6, at CometAPI: 0, the same: 0. The comparison includes estimates (≈) from their pages.

Image prices: CometAPI and Rendergrid
ModelResolutionCometAPIRendergridDifference
Nano Banana Pronano-banana-pro1K≈ $0.1072estimate on their page1$0.04Cheaper with us by 62%
Nano Banana Pro2K≈ $0.1072estimate on their page$0.04Cheaper with us by 62%
Nano Banana Pro4K≈ $0.192estimate on their page$0.07Cheaper with us by 63%
Nano Banana 2nano-banana-21K≈ $0.0536estimate on their page2$0.025Cheaper with us by 53%
Nano Banana 22K≈ $0.0808estimate on their page$0.04Cheaper with us by 50%
Nano Banana 24K≈ $0.1208estimate on their page$0.06Cheaper with us by 50%
Nano Banana 2.1nano-banana-2.11Kby tokens$6 per 1M tokens3$0.02can’t be compared
Nano Banana 2.12Kby tokens$6 per 1M tokens$0.03can’t be compared
Nano Banana 2.14Kby tokens$6 per 1M tokens$0.04can’t be compared
GPT Image 2gpt-image-21Kby tokens$24 per 1M tokens4$0.02can’t be compared
GPT Image 2.5gpt-image-2.51Knot availablenot on their pages5$0.025can’t be compared
  1. 1Nano Banana Pro. Amounts with the “≈” sign are from the variants table on the page (1K and 2K are one amount); there is an alias, nano-banana-pro-all—$0.096. Source: cometapi.com/models/google/gemini-3-pro-image. Checked on October 26, 2026.
  2. 2Nano Banana 2. Amounts with the “≈” sign are from the variants table on the page (there is also 0.5K—≈$0.036). Source: cometapi.com/models/google/gemini-3-1-flash-i…. Checked on October 26, 2026.
  3. 3Nano Banana 2.1. Rate: $6 per 1M tokens (output; input—$1.20 per 1M tokens). The model page gives a rate per token and names no amounts per image. Source: cometapi.com/models/google/nano-banana-2-1. Checked on October 26, 2026.
  4. 4GPT Image 2. Rate: $24 per 1M tokens (output; input—$4 per 1M tokens). The model page gives a rate per token and names no amounts per image. Source: cometapi.com/models/openai/gpt-image-2. Checked on October 26, 2026.
  5. 5GPT Image 2.5. We didn’t find a “GPT Image 2.5” page without a suffix; there are GPT Image 2.5 Sunburst and GPT Image 2.5 Flare, in the rows below. Source: cometapi.com/models/openai/gpt-image-2-5. Checked on October 26, 2026.

The difference is measured from the larger of the two prices, rounded down to a whole percent. The “≈” sign is an estimate that the provider’s own page gives. For GPT Image, quality and size differ between providers: each one’s conditions are in the footnote. We compare prices, not image quality. Nano Banana Flash, Nano Banana 2 Lite, and GPT Image 2 HD are not in the table: we haven’t checked the provider’s prices for them. Our own prices and the official Google and OpenAI prices are on the “Pricing” page.

03Terms

Payment, starter credits, and operating mode

What CometAPI’s pages say, next to our terms. Where a page is silent, we say so.

Terms: CometAPI and Rendergrid

ConditionCometAPIRendergrid
PaymentA bank card through Stripe; the minimum top-up is $10; the balance doesn’t expire, and the unused part, according to their guide, is refunded; 1,000 credits = $1source 1 source 2USDT (crypto top-up): the full amount sent is credited to the balance
Credits at no chargeAfter signing up, a $0.10 bonus is visible in the walletsourceThere’s no trial balance
Synchronous or asynchronousGoogle models go through /v1beta/models/{model}:generateContent, GPT Image through /v1/images/generations. The documentation has task polling for some image models (GET /v1/images/generations/{task_id}); how the result is collected for each of our models is not described on the checked pagessource 1 source 2 source 3Asynchronous: POST returns 202 and an ID; the result comes through polling GET /creations/{id} (no more than once every 5 seconds) or a webhook
Webhooksnot found: webhooks are described in the guide for video; for the image models in our table, the checked pages have no webhooksYes: webhook_url in every request; the creation.completed and creation.failed events; an HMAC-SHA256 signature over the timestamp and the whole request body
Failed requestnot checked: the rules for failed image requests were not found on the checked pagesIf a generation fails, the charge is returned to the balance automatically; a declined request is refunded the same way
LimitsThe limit numbers are not named on the checked pages; for a 429 response, they advise limiting concurrency and retrying with an increasing pausesourceBy default for a new account: 120 requests per minute and up to 100 generations queued or running; account limits can be adjusted to match your traffic
Result storagenot checked: the result storage period is not named on the checked pagesResult files are stored for one day

Also on their pages

  • For models with an official API the price is 0.8 of the official one; for spending above $3,000 a month, they suggest contacting support for a bigger discount. source
  • For models without an official API (Midjourney, Kling, Luma, and others), payment is per call, and CometAPI sets the price. source

Our terms in detail are in the documentation.

04Strengths

Where we’re stronger, and where CometAPI is

Only what can be verified from public pages and our documentation.

Where Rendergrid is stronger

  • The price is stated per image and resolution for every model in the table. At CometAPI, for Nano Banana 2.1 and the GPT Image models the page gives a per-token rate, and for Nano Banana Pro and Nano Banana 2, approximate amounts with the “≈” sign.
  • The result arrives asynchronously, and the webhook is signed and retried on a schedule. At CometAPI, webhooks are described in the guide for video, and for our image models they’re not on the checked pages.
  • Limits are stated as numbers: by default 120 requests per minute and up to 100 generations queued or running. CometAPI doesn’t name limit numbers on the checked pages.

Where CometAPI is stronger

  • The catalog is wider: 500+ models, including text, video, and music.
  • Card top-up through Stripe from $10; the balance doesn’t expire, and the unused part, according to their guide, is refunded.
  • A $0.10 bonus in the wallet after sign-up. We have no trial balance.
  • Two familiar request formats: Gemini-compatible and OpenAI-compatible.
  • According to their guide, for models with an official API the price is 0.8 of the official one (a 20% discount); above $3,000 a month they suggest discussing terms.

05Choosing

When to pick CometAPI instead

We write this page as a participant in the comparison, so we name separately the cases where CometAPI suits you better.

Pick CometAPI if

  • You need text, video, and music models on one key together with images.
  • You find it convenient to call models in the Gemini or OpenAI format with ready-made clients from those ecosystems.
  • You pay by card through Stripe, and a refund of the unused balance matters to you.

06Migration

Migrating to Rendergrid in three steps

If you decide to give it a try, here is what to change in the code. Parameters and responses are in the documentation.

  1. Key and address

    At CometAPI, requests go to https://api.cometapi.com (the Gemini format /v1beta/models/<model>:generateContent or the OpenAI-compatible /v1/images/generations) with its own key. For us it is https://api.rendergrid.io/api/public/v1 with an Authorization: Bearer header (or X-API-Key). The request and response format is different.

  2. Request

    Instead of a generateContent or OpenAI request body, call POST /images/generate: model, prompt, aspect_ratio, and resolution at the root of the JSON body; the webhook is webhook_url. Add X-Idempotency-Key.

  3. Result

    The answer doesn’t come as an image in the response body but as a 202 response with an ID: poll GET /creations/{id} (queued, processing, completed, and failed; links in result_urls) or accept the creation.completed webhook. Our files are kept for a day, so download them right away.

POST /images/generate · example request
IDEMPOTENCY_KEY="$(uuidgen)"
curl -X POST https://api.rendergrid.io/api/public/v1/images/generate \
  -H "Authorization: Bearer $RENDERGRID_API_KEY" \
  -H "Content-Type: application/json" \
  -H "X-Idempotency-Key: $IDEMPOTENCY_KEY" \
  -d '{
    "model": "nano-banana-2",
    "prompt": "a ceramic mug on a marble table",
    "resolution": "2K",
    "aspect_ratio": "1:1"
  }'

07FAQ

Frequently asked questions

How much does Nano Banana 2 cost at CometAPI and at Rendergrid?
According to CometAPI’s page, about $0.0536 per image at 1K; this is an estimate that the page itself gives (checked on ). At Rendergrid, Nano Banana 2 at 1K costs $0.025 per image. Prices change, so open the provider’s page before you decide: cometapi.com/models/google/gemini-3-1-flash-i….
How do you pay at CometAPI and at Rendergrid?
A bank card through Stripe; the minimum top-up is $10; the balance doesn’t expire, and the unused part, according to their guide, is refunded; 1,000 credits = $1. At Rendergrid: USDT (crypto top-up): the full amount sent is credited to the balance.
Does CometAPI give credits at no charge?
After signing up, a $0.10 bonus is visible in the wallet. At Rendergrid there’s no trial balance.
Does CometAPI work synchronously or asynchronously?
Google models go through /v1beta/models/{model}:generateContent, GPT Image through /v1/images/generations. The documentation has task polling for some image models (GET /v1/images/generations/{task_id}); how the result is collected for each of our models is not described on the checked pages. Rendergrid is asynchronous: POST returns 202 and an ID; the result comes through polling GET /creations/{id} (no more than once every 5 seconds) or a webhook.
How do I move from CometAPI to Rendergrid?
Three steps: 1) key and address; 2) request; 3) result. The details and an example request are in the “Migration in three steps” section on this page.
Why does CometAPI have no price per image for some models?
On CometAPI’s pages for Nano Banana 2.1 and the GPT Image models, a per-token rate is shown (for example, $6 per million output tokens for Nano Banana 2.1), and no amount per image is given. For Nano Banana Pro and Nano Banana 2, the pages give approximate amounts with the “≈” sign. So we show such figures as a guide or as a rate, not as a fixed price.
Where do these figures come from, and when were they checked?
All the CometAPI data comes from its public pages, with links in the “Sources” section. Checked on . Rendergrid wrote this page, so we give a source for every figure.

08Sources

Sources and check date

All the CometAPI data was taken from these pages, checked on . Prices change: open the provider’s page before you decide.

  1. 1
    Nano Banana Pro on CometAPIcometapi.com/models/google/gemini-3-pro-image · checked on October 26, 2026
  2. 2
    Nano Banana 2 on CometAPIcometapi.com/models/google/gemini-3-1-flash-image-preview · checked on October 26, 2026
  3. 3
    Nano Banana 2.1 on CometAPIcometapi.com/models/google/nano-banana-2-1 · checked on October 26, 2026
  4. 4
    GPT Image 2 on CometAPIcometapi.com/models/openai/gpt-image-2 · checked on October 26, 2026
  5. 5
    GPT Image 2.5 Sunburst on CometAPIcometapi.com/models/openai/gpt-image-2-5 · checked on October 26, 2026
  6. 6
    GPT Image 2.5 Flare on CometAPIcometapi.com/models/openai/gpt-image-2-5-flare · checked on October 26, 2026
  7. 7
    CometAPI: pricing guideapidoc.cometapi.com/pricing/about-pricing · checked on October 26, 2026
  8. 8
    CometAPI: account, top-up, and base URLapidoc.cometapi.com/overview/important-guidelines · checked on October 26, 2026
  9. 9
    CometAPI: limits and concurrencyapidoc.cometapi.com/guides/rate-limits-and-concurrency · checked on October 26, 2026
  10. 10
    CometAPI: documentation contentsapidoc.cometapi.com/llms.txt · checked on October 26, 2026
  11. 11
    CometAPI: home pagecometapi.com · checked on October 26, 2026

Found an inaccuracy? Write to support@rendergrid.io. The correction process is described in “About the editors”.

Try Rendergrid

One price per image and resolution, signed webhooks, an automatic refund for a failed request.

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