API Keys Explained: What Are They And How Are They Used?

Key Takeaways

• API keys can identify or associate applications and projects with API requests.
• Websites use API keys for services such as payments, maps, analytics, logistics and AI tools.
• API tokens are similar, although their exact purpose and permissions depend on the provider.
• API keys should be kept private and should not be exposed in public website code unless specifically designed for client-side use.
• Businesses should restrict, monitor and rotate API keys where possible.

API keys are credentials that applications can use when communicating with an Application Programming Interface, or API. They can help an API recognise which application or project is making a request and may also control access, track usage or apply limits.

For Singapore businesses, APIs are already used across many everyday digital tools, including payment gateways, logistics platforms, CRM systems, maps, analytics software and cloud services.

An API essentially acts as a controlled connection between two software systems. One system sends a request, while the other decides whether to accept it and what information or action to return.

Where an API uses a key, that key helps associate the request with an application, project or account.

A business owner may never see these interactions directly, but they happen constantly behind the scenes. When a customer pays online, checks a delivery status or loads a map on a company website, one or more APIs may be involved.

What Is An API Key?

An API key is a value issued by an API provider that can be used to identify or associate an application, project or account with API requests.

A key may look something like:

abc123XYZ789example

The actual format differs from one service to another.

When an API requires a key, the application includes it with the request so the provider can validate it and apply any associated rules.

Depending on the service, API keys can be used to:

• Identify or associate the application
• Track API usage
• Apply request limits
• Associate activity with an account or project
• Control access to certain services

Google Cloud notes that API keys can associate requests with projects for purposes such as billing and quotas, although standard API keys do not authenticate an individual user or other principal.

This is an important distinction. An API key may identify or associate an application or project with a request, but it is not always designed to function as complete authentication on its own.

How Do API Keys Work?

The process is usually fairly simple.

First, a developer or business creates an account with an API provider. The provider then generates an API key for a particular application or project.

When the application later needs information from an API that requires a key, it sends a request that includes the key.

For example, imagine a Singapore retailer using an external delivery platform.

When a shopper enters their postcode, the website may send that location to a delivery API. The API calculates the available shipping options and sends the results back.

The API key can help the delivery provider associate the request with the business using the service.

How Do You Use An API Key On A Website?

A website usually uses an API key by including it when sending a request to an external service.

The precise setup depends on the provider.

Some APIs require the key to be sent in a request header. Others use configuration files, software development kits or server-side environment variables.

Sensitive keys should generally be stored on the server rather than placed directly in public website code.

A safer structure often looks like:

Browser → Business Website Server → External API

The website server securely stores the credential and uses it when contacting the external provider.

By comparison, placing a sensitive key directly inside publicly accessible JavaScript can make it visible to anyone inspecting the website’s code.

Google Cloud advises developers not to hardcode sensitive API keys into client-side code or public source-code repositories because exposed keys can be copied and abused.

Some APIs are specifically designed for browser use and allow keys to be restricted to particular domains. In those cases, businesses should follow the security controls provided by the API platform.

What Is An API Token?

An API token is another type of credential used to authenticate or authorise API requests.

The terms API key and API token are sometimes used differently by different providers, so there is no universal distinction between them.

A token may represent:

• A user
• An application
• A login session
• A specific set of permissions
• Temporary access

GitHub personal access tokens, for example, can be assigned specific permissions and expiration dates.

This makes tokens useful when a system needs more control over exactly what an application or user can access.

What Is The Difference Between An API Key And API Token?

There is no universal definition followed by every API provider, but a general comparison looks like this:

An API key might tell a service which application or project is making a request.

A token may go further by representing particular permissions or a user session, depending on how the provider implements it.

Where Do Businesses Commonly Use APIs?

Businesses interact with APIs more often than they may realise.

Payment Processing

Online shops use APIs to communicate with payment gateways, confirm transactions and update order statuses.

Maps And Location Services

Businesses can use APIs to display maps, calculate routes or help customers find the nearest branch.

CRM And Marketing Platforms

A website enquiry form may automatically send customer information into a CRM or email marketing platform.

Logistics

Retailers can use APIs to calculate delivery fees, create shipments and track parcels.

Accounting Software

Invoices, payments and transaction records may be synchronised between different business systems using APIs.

AI Tools

Businesses increasingly use APIs to connect websites and internal systems to AI services for chatbots, document processing, automation and customer support.

This means APIs are not limited to large technology companies. Even a relatively simple SME website may rely on several APIs at once.

Are API Keys Secure?

API keys can be secure when handled correctly, but exposed credentials can create risks.

A leaked key could potentially result in:

Unexpected costs: Someone may use the key to make paid API requests.

Quota abuse: Attackers may consume the application’s request allowance.

Unauthorised access: A key with broad permissions could expose data or services.

Service disruption: Excessive requests can interfere with legitimate API usage.

The Cyber Security Agency of Singapore recommends measures such as encrypted connections, strong authentication, least-privilege access and regular security reviews when securing APIs.

The level of risk depends heavily on what a particular key can access. A key restricted to a public map service presents a different risk from one connected to customer records or internal business systems.

How Should Businesses Protect API Keys?

API keys should be treated as sensitive credentials rather than ordinary pieces of code.

Avoid public code: Do not place private keys in public repositories or openly accessible website files.

Restrict access: Limit keys to specific services, domains, applications or IP addresses where supported.

Apply least privilege: Give an integration only the permissions it actually needs.

Monitor activity: Watch for unexpected spikes in usage or requests from unfamiliar sources.

Rotate keys: Replace credentials periodically where appropriate and immediately if one may have been exposed.

Remove unused keys: Revoke old credentials when integrations are no longer active.

Businesses should also keep track of which vendors, developers or agencies have been given access to API credentials.

If an external developer finishes a project, for example, it may be sensible to revoke or replace credentials they previously used.

What Happens If An API Key Is Exposed?

If an API key appears publicly, businesses should assume someone could have copied it.

Simply deleting the webpage, message or repository where the key appeared may not be enough.

A sensible response usually includes:

1. Revoke or rotate the exposed key as soon as possible.
2. Update the affected website or application with the replacement credential.
3. Review usage logs for unusual traffic or activity.
4. Check permissions to understand what the exposed key could access.
5. Investigate the cause to prevent the same issue from happening again.

If personal data may have been accessed, Singapore businesses should also assess whether the incident creates notification or other obligations under the Personal Data Protection Act.

An exposed key does not automatically mean a data breach occurred, but businesses should investigate what the credential allowed and whether suspicious activity took place.

Do API Keys Expire?

Some API keys expire automatically, while others remain valid until they are manually revoked or replaced.

This depends on the provider.

Access tokens are more commonly designed to expire after a set period, while traditional API keys may remain active for much longer.

Even when expiration is not automatic, businesses can still introduce a rotation policy for important credentials.

This helps reduce the risk created by forgotten keys that may otherwise remain active for years.

Are API Keys The Same As Passwords?

Not exactly, although both should be protected.

A password usually authenticates a human user.

An API key generally identifies or associates an application, project or integration with API requests.

Some platforms also combine API keys with stronger authentication methods such as OAuth, service accounts or access tokens.

In that setup, the API key may identify the application or project, while another credential determines what the user or application is actually allowed to access.

Why Do API Keys Matter To Singapore Businesses?

Modern businesses often rely on interconnected software rather than a single standalone system.

A typical setup might look like:

Website → CRM → Payment Provider → Accounting Software → Delivery Service → Analytics Platform

Each connection can introduce another API credential.

As businesses add more SaaS tools, AI platforms and automated workflows, it becomes increasingly important to know:

• Which APIs are connected
• Who controls the credentials
• What data each integration can access
• Whether old keys are still active

Business owners do not need to understand every technical detail.

However, API credentials should still be treated as important digital assets, especially when they connect systems containing customer, payment or operational information.

Improving Your Business With API Keys

API keys help software systems communicate by identifying or associating applications and projects with requests, controlling access and tracking usage. They power many everyday business tools, from payment systems and maps to logistics platforms, cloud software and AI services.

For businesses looking to improve their digital presence, Listing.sg also provides another way to increase online visibility. Our Singapore business listing services help companies make their products and services easier for potential customers to discover.

Sources

• Cyber Security Agency of Singapore: Guidance on API security, authentication and access controls.
• Google Cloud Documentation: API key usage and security best practices.
• Amazon Web Services Documentation: API Gateway keys, quotas and usage controls.
• GitHub Documentation: Personal access tokens and permissions.
• Personal Data Protection Commission Singapore: Data protection and security obligations.

Frequently Asked Questions About API Key Usage

What Is An API Key In Simple Terms?

An API key is a credential that helps an online service recognise or associate the application or project making an API request. It may also be used to track usage or apply access restrictions.

How Do I Find My API Key?

API keys are usually generated from the developer, integration or credentials section of the service you want to connect to.

Is It Safe To Put An API Key On A Website?

Sensitive API keys should generally not be exposed in public website code. Where possible, store them securely on the server or use the restrictions provided by the API platform.

Some browser-based APIs are designed to use visible keys, but those keys should still be restricted according to the provider’s security guidance.

What Is The Difference Between An API And An API Key?

An API allows two software systems to communicate. An API key is a credential that may be used to identify, associate or control an application accessing that API.

Can Someone Use My API Key If It Leaks?

Potentially. Depending on the permissions attached to the key, someone could make unauthorised requests, consume your API quota or access connected services.

Do I Need An API Key For Every API?

No. Some APIs use API keys, while others rely on OAuth, access tokens, service accounts, signed requests or other authentication methods.