Secrets / Environment Variables

You’re reading the docs for Newly v1 (legacy), the classic newly.app builder. Using app.newly.app or Newly for Mac? Go to the Newly v2 docs. Credits, pricing and features differ between the two.

Secrets / Environment variables let you store configuration and secrets that your app needs, without showing them to other people, just like your personal passwords.

When to Use Secrets / Environment Variables

API Keys

Third-party service credentials

Configuration

Feature flags, URLs, settings

Secrets

Sensitive data that shouldn’t be in code

Environment-Specific

Different values for dev/staging/prod

In AI Prompts

Tell the AI to use secrets / environment variables but never add the secret to the prompt: Bad example:

Add weather data to the home screen, Here's the Openweather secret: nsadf98dsafjdsajnfiu

Good example: Before prompting, we add OPENWEATHER_API_KEY to the backend as a secret. The name of the secret is OPENWEATHER_API_KEY.

Add weather data to the home screen. Use the OPENWEATHER_API_KEY
environment variable for the API key.

Secrets / Environment Variables by Backend Type

How you manage environment variables depends on which backend system you’re using.

Which backend am I using? If you see a “Database” button in the preview header, you’re on Liquid Backend. Otherwise, you’re using Supabase. See Backend Systems.

Liquid Backend

With Liquid Backend, environment variables are split between frontend and backend:

Frontend Variables

For variables used in your React Native code:

Open Settings

Click **Database **and go to Secrets in the project menu

Add Variable

Enter the variable name and value:

Name: GOOGLE_MAPS_API_KEY
Value: your_api_key_here

Save

Click Save to store the variable, it is now accesible by the backend services.

Supabase Environment Variables

Supabase

Supabase credentials are managed through OAuth:

After connecting Supabase

Click More → **Environment Variables **and add your secrets.

Example

Add name OPENAI_API_KEY and value **sk-… **and save.

Using Public Secrets / Environment Variables in Frontend

Accessing Variables

All frontend environment variables are specified in app.json and accessed the same way:

import Constants from 'expo-constants';

// Access any environment variable
const apiKey = Constants.expoConfig?.extra?.MY_API_KEY;
const baseUrl = Constants.expoConfig?.extra?.API_BASE_URL;

With Default Values

const apiUrl = Constants.expoConfig?.extra?.API_URL ?? 'https://api.example.com';

Best Practices

Never hardcode secrets

API keys, passwords, and tokens should always be in environment variables, not in your code.

Use descriptive names

Use clear names like STRIPE_PUBLIC_KEY instead of KEY1

Separate frontend and backend secrets

Only public keys belong in frontend environment variables. Server-side secrets go in your backend.

Document required variables

Keep track of which environment variables your app needs for deployment.

Troubleshooting

Variable returns undefined

Check the variable name matches exactly (case-sensitive)
Ensure you saved after adding the variable
Reload the preview after changes

API key not working

Verify the key is correct (copy-paste from source)
Check if the key has proper permissions/scopes

Secret exposed in code

If its not a “public secret”, contact support in Newly

Backend Systems

Understand Liquid Backend vs Supabase

Supabase Integration

Full Supabase setup guide

Getting Started

Features

Troubleshooting

Integrations

Subscriptions (RevenueCat)

Advanced

Secrets / Environment Variables

When to Use Secrets / Environment Variables

API Keys

Configuration

Secrets

Environment-Specific

In AI Prompts

Secrets / Environment Variables by Backend Type

Liquid Backend

Frontend Variables

Supabase Environment Variables

Supabase

Using Public Secrets / Environment Variables in Frontend

Accessing Variables

With Default Values

Best Practices

Troubleshooting

Backend Systems

Supabase Integration

​When to Use Secrets / Environment Variables

API Keys

Configuration

Secrets

Environment-Specific

​In AI Prompts

​Secrets / Environment Variables by Backend Type

​Liquid Backend

​Frontend Variables

​Supabase Environment Variables

​Supabase

​Using Public Secrets / Environment Variables in Frontend

​Accessing Variables

​With Default Values

​Best Practices

​Troubleshooting

​Related

Backend Systems

Supabase Integration

When to Use Secrets / Environment Variables

In AI Prompts

Secrets / Environment Variables by Backend Type

Liquid Backend

Frontend Variables

Supabase Environment Variables

Supabase

Using Public Secrets / Environment Variables in Frontend

Accessing Variables

With Default Values

Best Practices

Troubleshooting

Related