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 Cloudflare Email Service account for outbound transactional email
4. a Resend account for inbound email and contact management

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
• CLOUDFLARE_ACCOUNT_ID - Your Cloudflare account ID
• CLOUDFLARE_EMAIL_API_TOKEN - A secret with Email Sending: Edit
• OUTBOUND_EMAIL_PROVIDER - cloudflare (default) or resend
• RESEND_API_KEY - Your Resend API key for inbound email and contacts
• 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

Onboard each outbound sender domain in Cloudflare Email Service. The app sends from calendar@fwd2cal.com and drive@fwd2drive.com, so both domains must show Enabled and Configured under Email Sending.

Store the Cloudflare token in Firebase Secret Manager before deployment:

firebase functions:secrets:set CLOUDFLARE_EMAIL_API_TOKEN --project YOUR_PROJECT_ID

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

# Cloudflare Email Service (store the API token with functions:secrets:set)
CLOUDFLARE_ACCOUNT_ID=YOUR_CLOUDFLARE_ACCOUNT_ID

# 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 mocks Cloudflare outbound sending and Resend inbound processing 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.