Composio — Gmail, Slack, Calendar & more

What you get

9 everyday tools behind a single connect button. Each one uses OAuth (not API keys) — click Connect, approve in the popup, done. Your built app can then send email through your Gmail, post to your Slack, log rows to your Sheets, create Notion pages, and more — all triggered by normal prompts.

The 9 toolkits — when each makes sense

📧 Gmail — Send email as YOU

For solo founders, coaches, consultants who want outbound email to feel personal — from your inbox, with your signature, replies landing in your Gmail. Example: “After someone finishes my quiz, email their results from my Gmail — feel personal, not marketing-automated.”

📅 Google Calendar — Real scheduling

Any app that needs to check availability or create events on the user's calendar. Example: “Let people book a 30-min call with me. Show my real Google Calendar availability and auto-block the slot when they pick.” — replaces Calendly for simple cases.

💬 Slack — Push alerts to your team

Internal dashboards, ops tools, “notify me when X” apps. Example: “Every time a user signs up for the Enterprise plan, post their company name and size to my #sales channel.” Better than email alerts because Slack is where you already live.

📝 Notion — Your workspace as the app's database

Powerful combo: non-technical users can skip Supabase entirely for content apps — Notion becomes both the database AND the admin UI. Example: “Log every quiz result (name, score, answers) as a new row in my ‘Research’ Notion database so I can filter + pattern-match right in Notion.”

📊 Google Sheets — Your spreadsheet as backend

80% of early-stage founders run their business on Sheets. This lets the app push rows directly. Example: “Every form submission appends a new row to my ‘Leads’ Google Sheet. Include timestamp, email, and the question answers.” Your existing charts and filters just work.

📄 Google Docs — Generate reports

For report generators, proposal builders, AI writing tools. Example: “After the personality assessment, auto-generate a 2-page ‘Your Profile’ Google Doc — styled with my logo — and email them the share link.” The output lives as a real Doc they can edit and share.

💾 Google Drive — Own your files

For apps with file uploads where the user wants to own the storage. Example: “Let people upload a testimonial photo with their review. Save each to my Drive's ‘Testimonials’ folder — I own the files, no Supabase storage bill.”

📋 Linear — Feedback into tickets

Feedback widgets, bug reports, feature requests. Example: “Add a ‘Report a bug’ button. When clicked, auto-create a Linear ticket in my Engineering project with the user's report text and current URL.” Triage happens in Linear, not in your inbox.

🧲 HubSpot — Lead-gen pipeline

The classic capture-to-CRM flow. Example: “Every user who gives their email during the quiz becomes a HubSpot contact. Their score goes in as a custom property and their date-taken becomes last-contacted. My sales team filters for ‘high scorer + not contacted’ and reaches out.”

How to connect

Unlike Supabase/Stripe/PostHog/GitHub (paste an API key), Composio uses OAuth per toolkit. Marnix handles the OAuth apps — no setup on your side.

1. Open Integrations → Gmail, Slack, Calendar & more.
2. Find the toolkit you want. Click Connect.
3. A popup opens to Composio's consent page, which redirects to the service (Google, Slack, etc.) for auth. Approve.
4. Popup closes, tile flips to “Connected.” Done.

You can connect as many toolkits as you want. Each one is independent — disconnecting Gmail doesn't affect Slack.

Troubleshooting

• Popup closed without completing — your popup blocker intercepted the OAuth callback. Allow popups for marnix.ai and try again.
• Connected but actions fail — some toolkits need specific scopes (e.g. Slack needs chat:write for DMs vs channels). Disconnect + reconnect, grant all requested scopes.
• Want a toolkit that's not in the list — Composio supports 500+ services; we just bootstrapped 9 for now. Email us and we'll add it.