Awareness for the
agents you build
Your users say “Tell me when”. Reactive watches, and wakes your agent the moment it happens.
Tell me when
Reactive watches for change and tells your agent the moment it happens.
Reactive monitors markets, crypto, shipping and weather, and alerts your agent when a value changes.
The world never stops changing.
Your agents should not have to keep checking.
Agents learn about the world by checking for change. Reactive reverses the flow: instead of asking what happened, your agent knows the moment it does.
Name the moment. Reactive notices it.
Name the moment
Describe what should wake your agent: as a sentence in the app, with one API call, or from the agent itself through the Reactive skill.
Tell me when BTC falls below 60,000
Reactive notices
Reactive watches the source continuously, so your agent doesn't have to. Each source is read as often as it allows, and every monitor on it shares that read.
Your agent responds
The moment it happens, your agent receives a single signal: what changed, its previous and new value, and where it came from.
BTC fell below 60,000
60,214 → 59,872 · just now
via webhook, Slack, email or in app
If it changes,
Reactive can notice it.
Markets, crypto, weather, shipping and public web pages, with more of the world added every month.
Crypto
Tell me when BTC falls below 60,000
Stock price
Tell me when NVDA drops 5% in a day
SEC filings
Tell me when Apple files an 8-K
Shipment tracking
Tell me when the parcel hasn’t moved in three days
Daily forecast
Tell me when rain is forecast in Austin tomorrow
Earnings
Tell me when Tesla beats its earnings estimate
Web page
Tell me when a competitor changes their pricing page
Insider transactions
Tell me when a Microsoft director sells shares
Current weather
Tell me when it drops below freezing in Denver
Company news
Tell me when there’s news about Shopify
IPO calendar
Tell me when a new IPO is scheduled this week
- Your ideaSomething we don’t watch yet? Tell us →
Delivered where your agent listens.
Every signal is complete: your agent can act on it without fetching anything else.
Where alerts go
X-Signature: t=1759400000,v1=5257a8…8bd
X-Delivery-Attempt: 1
{
"event_type": "price.threshold_crossed",
"entity": { "name": "Apple Inc." },
"previous_state": { "price": 199.87 },
"current_state": { "price": 200.12 },
"observed_at": "2026-09-04T14:31:02Z",
"evidence": [{ "source_id": "market_data_feed" }]
}The change itself
The previous and new value, not a page to re-read.Where it came from
The evidence behind every signal.Signed, and retried
Verify it came from Reactive. If you’re down, it retries for a day.Kept for 90 days
Replay any signal, or send a test one first.Questions
Anything else? Contact us.
What is Reactive?
Reactive gives the agents you build awareness of the world. Your users describe the moment that matters; Reactive watches for it continuously; when it happens, your agent receives a signal with exactly what changed.
How is this different from polling?
Polling asks the same question on a schedule and pays for every answer, including the many that say nothing changed. Reactive inverts that: your agent spends nothing while the world is quiet and hears the moment it isn’t.
Search tools now offer monitoring. How is Reactive different?
Search is built to find information. Reactive is built to detect change, and to describe it precisely: the previous value, the new value, when it happened and the evidence behind it, delivered reliably wherever your agent listens. Pricing follows the same idea: you pay for what you watch, not for how often we look.
What can Reactive notice today?
Markets and crypto, weather, shipping across more than 3,500 carriers, and public web pages. New datasets are added every month.
How quickly will my agent hear about a change?
As quickly as the source allows. Each dataset is read on its own schedule, and every user’s monitors share that one read, so watching closely costs nothing extra.
Which agents does it work with?
Any agent that can receive a webhook or call an API. Agents can also ask to become a design partner themselves, with one API call.
What does it cost?
You pay for each active monitor. Checks are free and unlimited, however often a source is read. Design-partner pilots are $2,000 for 60 days, credited to your first year. Platform plans start at $1,000 a month. When Reactive opens, a free plan will cover 100 monitors.
How does the design-partner program work?
We’re working closely with a small number of teams building agent products. Tell us what you’re building and we’ll set up a call. Pilots run 60 days: we wire Reactive into your agent with you, and the fee is credited to your first year.
Build an agent that notices the world
We’re working closely with a small number of teams building agent products.