Every time an app shows you the weather, takes a card payment, or sends a prompt to an AI model, there is a good chance an API key made it possible. API keys are one of the most common ways to make software talk to other software. 

Unfortunately, API keys are also one of the most commonly leaked secrets on the internet. A key pasted into the wrong file or shared in a chat message can give a stranger access to your account and your data.

This guide explains what API keys are in detail, what they are used for, how they compare to OAuth and JWT, and how you can keep your API keys safe.

What Is an API Key

An API key is a long, unique string of characters that a software or service gives you so you can connect with another application through an Application Programming Interface (API), allowing communication and data exchange between two programs. When one software sends a request to another, the service checks the API key, confirms it is valid, and then either responds to or rejects the request.

API key is similar to a hotel room key. The card does not care who is holding it. If it is valid, the door opens.

What Is an API Request 

Here is what a typical API request looks like in simple terms:

1. Your software wants data from a service, such as a weather forecast.
2. It sends a request with the API key attached, usually in a request header.
3. The service checks the key against its records.
4. If the key is valid and allowed to do that action, the service sends back the data.

What Are API Keys Used For

API keys do three main jobs: They prove who is calling APIs, they record how much each caller uses, and they help the provider stop misuse.

Authentication

The first job of an API key is to identify the caller. Without a valid key, most APIs will refuse to respond at all. Stripe is a clear example. If a request doesn’t include a valid key, Stripe returns an invalid request error, and if it includes a deleted or expired key, Stripe returns an authentication error.

Usage Tracking

Since every API request carries an API key, the API provider can count exactly how many requests each key makes. This is how usage-based pricing works. AI providers, cloud platforms, and data APIs use it to bill you for what you use.

Separate keys also make tracking more useful on your side. OpenAI recommends a unique API key for each team member on an account and does not support sharing keys. When each person or project has its own key, you can see who used what and spot unusual activity faster.

Abuse Prevention

API keys give providers a way to control access. They can set rate limits per key, block keys that behave strangely, and let you shut off a single key without affecting anything else. Many providers also let you add restrictions to a key. 

Which Platforms Usually Have API Keys

Almost any service that offers an API connection will give you some kind of API key or token, and most modern platforms have API connections. Today, the following categories are the most popular when API keys are discussed:

AI Model Providers

AI model providers such as OpenAI and Anthropic require an API key with every request. Usage is billed to the account that owns the key, so a leaked key means someone else can run up your bill. OpenAI warns that exposing a key lets malicious users make requests on your behalf, which may lead to unexpected charges or compromise of account data.

Payment Platforms 

Payment platforms handle money, so key types matter a lot here. For instance, Stripe separates keys by purpose: Publishable keys can be used in client-side code, while secret keys must stay in server-side code and should never be exposed on a website or embedded in a mobile app. 

Cloud Platforms 

Cloud platforms use keys and credentials to control access to servers, storage, databases, and other services. AWS access keys have two parts, an access key ID and a secret access key, and both are used during authentication. Google Cloud issues API keys for many of its APIs, and some Azure services, such as Azure AI services, also support key-based access.

Developer Tools 

Developer platforms issue access tokens that work much like API keys. They let scripts, command-line tools, and deployment pipelines act on your account. GitHub calls these personal access tokens, and Vercel and Netlify offer similar tokens for automated deployments.

Data APIs 

Weather services, mapping platforms, and geolocation tools usually give out API keys, often with a free tier and paid usage above it. Some of these keys are designed to run in a browser or mobile app, such as a map embedded on a website.

API Keys vs. OAuth vs. JWT

API keys are often paired with OAuth and JWT. Here’s what each term means:

API keys identify an application or project. They are simple to create and use, which makes them a good fit for server-to-server calls and internal tools. The trade-off is that a basic key usually has no built-in expiry and no link to a specific user. For tracking, each user has their own separate key.

OAuth is an authorization framework. It lets a user give an app or platform limited access to their account on another software or service without sharing their password. When you click “Sign in with Google” on a platform, it’s usually OAuth. The app receives an access token with specific permissions, and the user can revoke it or “Sign out” at any time.

JWT (JSON Web Token) is a token format, not a login method on its own. A JWT is a signed package of information, such as a user ID and an expiry time, that a server can verify without looking anything up in a database. JWTs are often used as the access tokens inside OAuth flows or as session tokens after a user logs in.

How to Keep Your API Keys Safe

Most API key leaks are not sophisticated attacks. They happen because a key ended up somewhere it should not be. The rules below help keep your API keys safe.

1. Never Hardcode a Key in Your Source Code

A key written directly into your code travels everywhere your code goes: every copy, every branch, every backup. Store your API keys in environment variables or a dedicated secrets manager instead. Your code reads the key at runtime, and the key itself never appears in the codebase.

2. Never Put Keys in URLs

Some APIs accept keys as part of the URL, but that’s not a good idea. URLs get saved in browser history, server logs, and analytics tools. Send your API key in an HRRP header or through a client library instead.

3. Use One Key Per Purpose 

If one key powers your website, your internal scripts, and your staging environment, a leak in any of them exposes all of them. You also cannot revoke it without breaking everything at once. Give each project, environment, and team member its own key. 

4. Scope Your Keys to the Minimum Permissions Needed

A key should only be able to do the job it was created for. If a tool only needs to read data, it should not have permission to write or delete it. If a third party only monitors disputes, you can give it a restricted key with read-only access to dispute data, so an attacker who stole that key would be limited to read-only calls.

5. Rotate Keys on a Schedule

Rotation means replacing an old key with a new one and retiring the old one. It limits how long a key stays useful if it’s leaked, even if you never find out it leaked. The safe way to rotate is to create the replacement first, update your applications to use it, and revoke the old key only after you confirm the new one works. 

6. Monitor Usage Dashboards

Most API connection providers show usage per key in their dashboards. Check them regularly. A sudden spike in requests, calls from unfamiliar locations, or charges you cannot explain are often the first signs of a leaked key.

7. If a Key Leaks, Rotate First and Investigate Second

When a key is exposed, every minute it stays active is a minute someone can use it. Revoke or rotate the leaked API key immediately, then investigate how it leaked.

Secure and Manage Your API Keys with WorkflowFiesta

When your AI agents connect to tools like Gmail, Jira, GitHub, and your AI models like ChatGPT and Claude, they need credentials to do it. WorkflowFiesta is built so those credentials stay protected at every step.

Encrypted Credential Store: API keys, OAuth tokens, and passwords are decrypted only at runtime inside isolated containers, and they are never visible in conversation history, logs, or to other users. Once you save a key, its value is not displayed again.

Secure Credential Collection: When a workflow needs a new credential, a secure in-chat form collects it directly into the encrypted store, never through conversation history.

Automatic Redaction: If anyone pastes an API key, password, or sensitive token into a conversation, WorkflowFiesta detects and redacts it before it is stored or shared. That covers one of the most common ways keys leak on a team.

Isolated Execution: Each workflow runs in its own disposable container with no shared memory between runs, and the container is destroyed when the workflow completes.

Access Controls and Oversight: Owner, Admin, and Member roles each have defined permission boundaries, and nothing is on by default. AuthCop checks every agent action before it touches a connected system, blocking destructive actions and sending high-privilege requests to an admin first. Audit logs record who triggered each action, what ran, what it cost, and when, and can be exported as CSV.

Bring Your Own Model (BYOM): You can connect your own Anthropic, OpenAI, or AWS Bedrock API keys, so prompts go directly to your provider under your account. Spend limits can be set per user, per workflow, per agent, and org-wide, which keeps usage under control even if something goes wrong.