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The JavaScript library forExtensionPay.com, a service to easily add payments to browser extensions. So far ExtensionPay has earned extension creatorsover $500k and counting!

// Example code// your-extension/background.jsconstextpay=ExtPay('your-extension-id');extpay.startBackground();extpay.getUser().then(user=>{if(user.paid){// ...}else{extpay.openPaymentPage()}})

Below are directions for using this library in your browser extension. If you learn better by example, you can also view the code for asample extension. This library usesMozilla's webextension-polyfill library internally for compatability across browsers which means it should work on almost all modern browsers.

"It hasn't even been 1 year yet and I'm already going topass $4,000 in annual subscriptions on an extension that I never in a million years thought I would be able to make a penny from. Thanks so much for creating this tool! I would not have even tried to monetize if I had to use Stripe directly, and you made it so easy.It took less than an hour to set it up and test it. Definitely have plans to create more extensions now that I know howeasy it is to monetize them." - David, Neobuyer extension

1. Install
2. Configure yourmanifest.json
3. AddExtPay tobackground.js (required!)
4. Useextpay.getUser() to check a user's paid status
   • user object properties
5. Useextpay.openPaymentPage() to let the user pay
6. Useextpay.getPlans() to list available payment plans
7. Useextpay.onPaid.addListener() to run code when the user pays
8. Useextpay.openPaymentPage() to let the user manage their subscription
9. Useextpay.openTrialPage() to let the user sign up for a free trial
10. Useextpay.openLoginPage() to let the user log in if they've paid already

Note: ExtPay.js doesn't contain malware or track your users in any way. This library only communicates with ExtensionPay.com servers to manage users' paid status.

If you like this library, please star it! ⭐️ It helps us out :)

npm install extpay --save

If you're not using a bundler, you can copy thedist/ExtPay.js file into your project (orExtPay.module.js for ESM /ExtPay.common.js for Common JS).

ExtPay needs the following configuration in yourmanifest.json (for both manifest v2 and v3):

{"permissions": ["storage"    ]}

ExtPay will not show a scary permission warning when users try to install your extension.

Note: For Firefox, you may have to include"https://extensionpay.com/*" in your extension manifest's "permission" for ExtPay to work properly.

If you have a"content_security_policy" in your manifest or get aRefused to connect to 'https://extensionpay.com...' error, you'll have to addconnect-src https://extensionpay.com to your extension's content security policy.See Mozilla's documentation for more details.

You need to putExtPay in your background file, often named something likebackground.js. If you don't includeExtPay in your background file it won't work correctly. If you're using a bundler you canimport 'ExtPay' orrequire('ExtPay') right in yourbackground.js.

With either Manifest V3 or Manifest V2 you'll need tosign up and register an extension. When you register an extension you'll create an extension id that you'll use when initializingExtPay. We'll usesample-extension as the extension id in the following examples.

{"background": {"service_worker":"background.js"    }}

// background.jsimportScripts('ExtPay.js')// or `import` / `require` if using a bundlervarextpay=ExtPay('sample-extension');// Careful! See note belowextpay.startBackground();

Note about service workers: In the example aboveextpay will become undefined when accessed in service worker callbacks. To useextpay in service worker callbacks, redeclare it like so:

chrome.storage.local.get('foo',function(){varextpay=ExtPay('sample-extension');// ...})

Make sure not to useextpay.startBackground() in callbacks — it should only be called once.

If you're not using a bundler, addExtPay.js tomanifest.json:

{"background": {"scripts": ["ExtPay.js","background.js"]    }}

// background.jsconstextpay=ExtPay('sample-extension')extpay.startBackground();

This method makes a network call to get the extension user's paid status and returns auser object.

extpay.getUser().then(user=>{if(user.paid){// ...}else{// ...}})

or useawait:

asyncfunctionfoo(){constuser=awaitextpay.getUser();if(user.paid){// ...}}

It is possible forextpay.getUser() to throw an error in case of a network failure. Please consider this possibility in your code e.g.extpay.getUser().then(/* ... */).catch(/* handle error */)

Theuser object returned fromextpay.getUser() has the following properties:

Opens a new browser tab where the user can pay to upgrade their status.

extpay.openPaymentPage([planNickname])

The payment page looks like this:

The plan buttons take you to a Stripe Checkout page:

Note:extpay.openPaymentPage() can fail to open the tab if there is a network error. Please consider this possibility in your code.

You can optionally include yourplanNickname as an argument toextpay.openPaymentPage(planNickname) to directly open the Stripe payment page for that plan. For example:extpay.openPaymentPage('my_plan_nickname'). Plan nicknames can be edited in the ExtensionPay.com extension settings page.

While developing your extension in test mode, you will need to enter your account password in order to proceed to the Stripe Checkout page. This is to prevent fraudulent access to your extension. You can useStripe's test cards in order to test the payment experience in development.

It is best to open the payment page when the user has a clear idea of what they're paying for.

Depending on how you configure your extension, users that have paid before can log in to activate their paid features on different browsers, profiles, or after uninstalling/reinstalling.

You should turn on as manypayment methods in your Stripe settings as possible to maximize your revenue.

Also seeour guide for how to create coupon / discount codes for your extensions.

For example, an extension with a $10 monthly and $99 yearly plan might look like this:

>awaitextpay.getPlans();[{unitAmountCents:1000,currency:'usd',nickname:null,intervalCount:'month',interval:1},{unitAmountCents:9900,currency:'usd',nickname:null,intervalCount:'year',interval:1}]

The specification for plans looks like this:

interfacePlan{unitAmountCents:number;currency:string;nickname:string|null;interval:'month'|'year'|'once';intervalCount:number|null;}

If you want to run some code when your user pays for the first time, useextpay.onPaid.addListener():

extpay.onPaid.addListener(user=>{console.log('user paid!')})

To use this feature, you will need to include the following content script configuration in yourmanifest.json:

{"content_scripts": [        {"matches": ["https://extensionpay.com/*"],"js": ["ExtPay.js"],"run_at":"document_start"        }    ]}

The content script is required to enableextpay.onPaid callbacks. It will add a permissions warning when installing your extension. If you're using a bundler, you can create a file called something likeExtPay_content_script.js that only containsimport 'ExtPay' orrequire('ExtPay') and use that in the"js" field above.

You can add as many callback functions as you want.

Note:onPaid callbacks will be called after a user pays as well as after a user "logs in" (e.g. activates their paid account on a different browser/profile/install). This may change in the future -- if you'd like this to work differently, please contact me with a detailed explanation of your use case :)

If your extension is configured for subscription payments, you should let the user manage/cancel their subscription from within the extension with the same function you used to let them pay:

extpay.openPaymentPage()

The subscription management page looks something like this:

Note: please read thedetailed docs on subscriptions here.

If you want to give your users a trial period of your extension, you can useextpay.openTrialPage(), which looks something like this:

The user will be sent an email with a link that they can use to start their free trial. Once the user clicks the link, you can use thetrialStartedAt property fromextpay.getUser() in your extension to check if the trial has expired.

For example, if you wanted a 7 day trial period, you could use a check like this:

constextpay=ExtPay('sample-extension');extpay.getUser().then(user=>{constnow=newDate();constsevenDays=1000*60*60*24*7// in millisecondsif(user.trialStartedAt&&(now-user.trialStartedAt)<sevenDays){// user's trial is active}else{// user's trial is not active}})Afterusersstartatrial,theuserobjectwillhavethe`trialStartedAt`propertypopulated.Ifusersuninstallandreinstallyourextensionandthenattempttostartanewtrialusingthesameemailtheypreviouslyused,theywillbeinstantly "loggedin" to their existing free trial without needing to confirm instead of starting a new trial or being rejected. Their `trialStartedAt` will be the same. If this is confusing, please try it out in development!

Note thatextpay.openTrialPage(displayText) takes an optional string argument that is displayed to the user on the trial page. For example,extpay.openTrialPage('7-day') would change the trial prompt fromEnter an email to start your free trial toEnter an email to start your *7-day* free trial. This is meant to give your users a better idea of what they're signing up for.

You can also useextpay.onTrialStarted.addListener() to run functions when the user's trial starts. LikeonPaid, you need to include the following in yourmanifest.json to make it work:

{"content_scripts": [        {"matches": ["https://extensionpay.com/*"],"js": ["ExtPay.js"],"run_at":"document_start"        }    ]}

A page will open that will allow the user to enter the email they paid with to receive a magic login link. This page can also be accessed through the normal payment screen.

1. npm install
2. EditExtPay.dev.js
3. npm run dev
4. npm run dist before committing changes.