Set up your own OpenAI API key, step by step

What an API key actually is

An API key is a long string of characters, a bit like a password, that identifies you to an AI provider. Every time Bildplattform edits one of your photos, it sends the image to OpenAI together with your key, and OpenAI bills the few cents this costs to your account, not to ours. You are therefore not buying a plan from us and not buying credits from us. You hold your own contract with the provider, see every cent you spend, and can cancel or swap the key at any time. That is the whole idea behind bring your own key, and it is why the licence is a one-time purchase with no monthly fee.

Step 1: create an OpenAI account

Open https://platform.openai.com/signup in your browser. This is the developer platform of OpenAI, not the ChatGPT app, so an existing ChatGPT subscription does not help here and is not needed. An email address or a Google or Microsoft login is enough. Confirm the email, enter your name and, if asked, the name of your business. If you already have a ChatGPT login you can use the same credentials, but the API balance is kept separately.

Step 2: create the secret key

Once signed in, go to https://platform.openai.com/api-keys and click the button labelled Create new secret key. Give the key a name you will recognise later, for example Bildplattform, and leave the permissions at the default setting. After you confirm, the key is shown exactly once. Copy it immediately and paste it straight into Bildplattform, or into a password manager if you want to store it there first. If you close the window without copying, there is no way to see the key again; you would simply create a new one and delete the old one. An OpenAI key always starts with sk-, which is also how the app recognises it.

Step 3: store the key in Bildplattform

When you set up Bildplattform for the first time, the onboarding has a step called AI connection. Paste the key there and click Save and test connection. If you skipped that step earlier, open Settings, then the AI tab, and paste the key there. The app runs a short test call so you know right away whether the key works. The key is stored encrypted on your own installation. It is never forwarded to us, never shown in full again, and only ever used to send your images to OpenAI.

Step 4: top up a balance

A fresh OpenAI account has no balance, and without balance the key will not edit a single image. Go to https://platform.openai.com/settings/organization/billing, add a payment method and buy an initial balance. Ten euros is plenty to start with: at the standard setting that is roughly two hundred photos. The balance is prepaid, so you only ever spend what you have loaded, and a card on file does not mean OpenAI can charge you freely.

Step 5: set a spending limit, this matters

This is the step most guides leave out and the one we consider mandatory. Open https://platform.openai.com/settings/organization/limits and set a monthly budget that matches your real usage, for example 20 or 50 euros. You can also set a lower threshold at which OpenAI sends you an email. With the limit in place, a mistaken bulk upload, a shared key, or a colleague who gets enthusiastic can never turn into a surprise invoice. OpenAI simply stops accepting requests once the budget is reached, and you raise it deliberately if you need more.

Step 6, optional: automatic top-up

If you edit photos every week and do not want to think about the balance, you can enable auto recharge on the same billing page. It reloads a fixed amount whenever the balance drops below a threshold you choose. Combined with the spending limit from step 5 this is convenient and still safe. If you edit only occasionally, leave it off and top up by hand when the app reports an empty balance.

What it actually costs

Bildplattform offers three quality tiers, and the price per image is set by OpenAI, not by us. The figures below are the real model prices behind the pricing page and the comparison calculator:

• Budget: about 1.6 cents per image, roughly 1.60 EUR for 100 photos. Fine for quick drafts.
• Standard: about 5.1 cents per image, roughly 5.10 EUR for 100 photos. The recommended default for listings.
• Maximum: about 17.4 cents per image, roughly 17.40 EUR for 100 photos. For hero shots and print.

On top of the editing, the image analysis that decides what a photo needs costs a fraction of a cent per image and is barely visible on the bill. For an agent with ten listings a month, the whole thing usually lands in the single-digit euros. Subscription tools charge many times that for the same work, which is exactly what our cost article breaks down.

Common errors and what they mean

• Key saved but every edit fails: the account most likely has no balance yet. Check the billing page and top up. A key without balance is the single most common problem.
• Edits worked and then suddenly stop: the monthly spending limit from step 5 has been reached. Raise it on the limits page if the usage was intended.
• Error 429 or a rate limit message: OpenAI is throttling requests, either because of a zero balance, a new account with low limits, or many images sent at once. Wait a minute, confirm the balance and try a smaller batch. Limits rise automatically as the account earns history.
• The key is rejected when saving: check for a missing character from copying, a leading space, or a ChatGPT login instead of a platform key. An API key starts with sk- and is never your password.
• Invalid key after months of use: the key was deleted or rotated on the OpenAI side. Create a new one and replace it under Settings, AI.

A note on safety

Treat the key like a bank card. Do not paste it into emails or chat messages, do not put it on a shared drive, and create a separate key per installation if several colleagues use the tool. If you suspect a key has leaked, delete it at https://platform.openai.com/api-keys and generate a fresh one; the old one stops working instantly and Bildplattform only needs the new one pasted in once. Combined with the spending limit, the worst case of a leaked key is a capped bill and two minutes of work.

That is the entire setup. Ten minutes once, a spending limit you never think about again, and from then on every edit costs exactly what the provider charges and not a cent more.