fwd2cal

forward an email => get calendar event

That's it. No buttons, no clicking - just forward an email, and a calendar event gets added to your Google Calendar.

fwd2cal uses an LLM to parse the thread, generate a JSON of the event details, and then adds the event to your google calendar.

fwd2cal.com - running in production, free until it gets annoying/expensive to run.

fwd2cal.create.mp4

You can self host - it runs on firebase functions.

Features:

• Signup with an email: just email calendar@fwd2cal.com and you'll be sent a google auth link.
• Send from multiple email addresses: send add myworkemail@address.com in the subject line to calendar@fwd2cal.com, and then you can add events to your google calendar from another email address
• ICS attachment support: Forward emails with .ics calendar attachments to automatically add them to your calendar
• Multi-event extraction: Extract and add multiple events from a single email
• Email threading: Replies appear in the same email thread for better organization
• Completely private: No logging, or storage of any emails. All that is stored are your email addresses.
• That's it. The goal is to just do one thing correctly and stay out of the way of the user.

Self hosting setup

You will need:

1. a firebase project
2. an OpenRouter API key (for LLM access)
3. a Resend account for sending and receiving emails

When you deploy or run the emulator firebase emulators:start, Firebase will prompt you to set the required parameters:

• OPENROUTER_API_KEY - Your OpenRouter API key
• RESEND_API_KEY - Your Resend API key
• RESEND_SIGNING_SECRET - Resend webhook signing secret
• POSTHOG_API_KEY - (Optional) PostHog API key for analytics
• ENVIRONMENT_NAME - (Optional) Defaults to "production"

Configure Resend to forward incoming emails to your Firebase Functions webhook:

• In your Resend dashboard, set up email forwarding to: https://{your project name}.web.app/v2/resendInboundCallback
• be sure to copy the RESEND_SIGNING_SECRET after you set your callback url
• Make sure to configure your domain's DNS records in Resend to receive emails

Local setup

Create a functions/.env file with your local development credentials:

# Environment Configuration
ENVIRONMENT_NAME=local

# API Keys
OPENROUTER_API_KEY=sk-or-v1-YOUR_API_KEY

# Resend
RESEND_API_KEY=re_YOUR_API_KEY
RESEND_SIGNING_SECRET=whsec_YOUR_SECRET

# PostHog Analytics (optional)
POSTHOG_API_KEY=phc_YOUR_API_KEY

Also - you're probably going to want to save your credentials from https://console.cloud.google.com/apis/credentials to: functions/auth/v2-google-auth-credentials.json.

You want to make sure your redirect_uris are setup correctly. It is a list, [0] should be the default from firebase, [1] should be http://127.0.0.1:5002/v2/oauthCallback for local development, and [2] should be the prod url.

Testing

export TESTER_PRIMARY_GOOGLE_ACCT="your@gmail.com"
export TESTER_SECONDARY_EMAIL_ACCT="anotherEmailAddressThatYouUse@anything.com"
cd functions
npm test

Make sure you authorize your google account in 30 seconds after starting the test so the tests can run.

The test suite uses a mock Resend client to simulate email sending and receiving without making actual API calls.

To test scheduled functions (note: token refresh is currently disabled):

firebase functions:shell
v2refreshTokensScheduled()

Contributing

All contributions are welcome. I will do by best to keep main stable.

Where you can help:

• functions/util/prompts.js - Prompt engineers can help here. If you notice fwd2cal fail to add your event correctly, consider adding examples to the prompts to improve the AI's understanding.
• Timezones - The current timezone detection could be improved for better accuracy across different formats and locations.
• Multiple calendars: Right now all events are added to the default calendar - the AI could potentially understand context and select an appropriate calendar.
• Find a way to add a test for the oAuth refresh tokens.

Author

This was written by @moeadham to get familiar with firebase and structured data from LLMs - training for a much larger project I'm working on.