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Horizon’s Slack app is the fastest way to use Horizon — no code, no API key to manage yourself. Ask questions in plain English in a channel, a DM, or with a slash command, and the same enrichment engine that powers the REST API and MCP server does the work.
Building your own agent or workflow instead? See the Quickstart for the REST API, or MCP Install to wire Horizon into Claude, Cursor, or another MCP client.

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1. Click Add to Slack

Go to lite.gravitygtm.com/api/slack/install. Horizon’s account and Slack’s own OAuth consent screen are two separate steps, but this one link walks you through both in order:
  • Already have a Horizon account, signed in? You’ll land straight on Slack’s consent screen — skip to step 3.
  • New here, or not signed in? You’ll be sent to sign in or create an account first, then straight back to this same link automatically — pick up at step 2.

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2. Create an account and pick a plan

Signing up takes an email/password (or SSO) Clerk account, then a plan:
  • Free trial — 1,000 credits, $0. Requires a card on file (Stripe Checkout in setup mode) to deter abuse, but charges nothing.
  • A paid pack — see Credits & Pricing for the full list (49/49/199/$499, or custom invoicing at volume).
Either one takes you through Stripe Checkout and back to your dashboard — your account, API key, and credit balance all exist the moment that completes, whether or not you ever connect Slack at all. From your dashboard, click Add Horizon to Slack to pick up exactly where step 1 left off.
Already have a Horizon API key from the REST/MCP side? Sign in, and the dashboard’s “link an existing key” option connects it to your account instead of starting a new plan — no need to pay twice.
Horizon requests the bot scopes it needs to reply in channels/DMs, react with a status emoji, read thread history it’s already participating in so follow-ups work without re-mentioning it, read a dragged-in file’s content when you ask it to work through one, and upload CSV exports for large result lists — nothing beyond what those features require. Approve it for your workspace and the install completes immediately — there’s no separate in-Slack signup step anymore, since your account and credits were already set up in step 2.

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4. Ask your first question

Three ways to talk to Horizon:
  • @mention it in any channel it’s in: @Horizon find the CEO of Acme Corp
  • DM it directly, no @mention needed
  • Slash command: /usehorizon find the CEO of Acme Corp
Horizon replies in a thread under your question (or under the message it echoes back, for a slash command), with a short progress update if the request takes a few tool calls, and a final answer that ends with what it spent — e.g. _Spent 27 credits · 173 remaining_.

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Buying more credits

When your balance runs low, ask Horizon (it’ll tell you when you’re out) or DM it any time — every low-balance reply includes a direct top-up link, and your dashboard’s Billing page always has the full pack list too. See Credits & Pricing for pricing; Slack, REST, and MCP all draw from the same balance, so a pack bought from Slack works everywhere else too.

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What’s next

See Using Horizon in Slack for the full rundown — compound requests, list/batch processing, the spend-confirmation card, and the free-tier daily limit.