The Signal API
Programmatic REST access to the cybersecurity market dataset behind The Signal — funding rounds, M&A, companies, investors, and the analytics built on them. Build market maps, deal sourcing, and account enrichment on the same data that powers the dashboard.
Overview
The Signal API is a read-only REST API over Return on Security's curated cybersecurity
market data — the same dataset behind
The Signal dashboard and the weekly
Return on Security newsletter. Every endpoint is a GET that returns JSON,
authenticated with a Bearer key. The base URL is:
https://signal.returnonsecurity.comThe dataset spans seven domains across 18 public endpoints:
What you can build
The Signal API turns the business of the cyber industry into a queryable dataset. A few things teams build on it:
For investors & corporate development
- Market mapping — a live landscape of every funded company in a cybersecurity category, with round sizes, investors, and timing. /companies · /category-data · /top-funding-rounds
- Deal sourcing & follow-on — track newly funded startups and stage velocity to find your next entry before the next round. /funding/history · /stages/distribution
- Consolidation & acquirer tracking — who's buying, what buyer types are active, and the most acquisitive players in the market. /top-acquisitions · /top-acquirers-by-volume · /buyer-type
- Investor benchmarking — league tables and portfolio activity by firm. /top-investors · /investors/{name}
For go-to-market teams
- Budget-signal targeting — surface security companies by stage and category right after a raise, when budget is fresh. /companies · /category-data
- Account enrichment — attach funding history, investors, and valuation context to your CRM records. /companies/{name} · /investors
For founders & operators
- Benchmark your raise — compare your round against stage percentiles for your category. /funding-stage-percentiles · /ranges/breakdown
- Category & competitive intel — track the players and momentum in your space. /company-type · /category-data
For analysts, researchers & press
- Sector trends & rankings — funding totals, M&A activity, and league tables for reports and stories. /charts · /top-funding-rounds · /top-acquisitions
Why The Signal API
Quickstart
1. Get a key. Go to
Account → Developer → API and
mint a key. It looks like ros_live_… and is shown once — store it somewhere safe.
2. Export it so you never paste it inline:
export ROS_API_KEY="ros_live_…"3. Make your first call:
curl -H "Authorization: Bearer $ROS_API_KEY" \
"https://signal.returnonsecurity.com/api/v2/companies?limit=10"
A successful response is a JSON body plus headers that tell you how fresh the data is
(X-Data-Freshness), how much quota you have left (X-Quota-*), and a
request id (X-Request-Id) to quote if you need support. Browse every endpoint,
parameter, and schema in the API Reference.
Authentication
Every request authenticates with an Authorization: Bearer ros_live_… header.
Keys are minted, labelled, and revoked at
your account. Access is checked on
every request against your live entitlement (Enterprise, or an active API add-on) —
so revoking a key or a lapsed add-on takes effect immediately, not at some cache expiry.
$ROS_API_KEY) as shown above. A leaked key can be revoked and
re-minted from your account at any time.
Plans & access
The API is a paid product. Every plan that includes it gets the full curated dataset and all 18 endpoints — the difference between plans is the request allowance, not the data.
| Plan | API access | Quota |
|---|---|---|
| Free | Dashboard only — no API | — |
| Pro / Team + API add-on | Full API, all endpoints | 1,000/day · 30,000/mo |
| Enterprise | API included | Unlimited |
Add the API to a Pro or Team plan for $79/mo from your account; Enterprise includes it. Need more than 30k/mo? That's what Enterprise is for — it lifts the caps entirely.
Premium fields
A few response fields are premium intelligence — they're part of the paid
dataset and populated for any API caller (the keys are always present; values are
null on the free dashboard). Today that's the investor
government-linkage set on /investors:
government_linked_tier (govt_chartered / defence_cvc /
sovereign_wealth), government_linked_country, and
government_linked_since — non-null only for investors in the curated
government-linked taxonomy. Each premium field is marked in the
API Reference.
Rate limits & quotas
Each key is metered against two windows. Defaults (Enterprise is uncapped):
| Window | Limit | Resets |
|---|---|---|
| Daily | 1,000 requests | 00:00 UTC |
| Monthly | 30,000 requests | 1st of month, UTC |
Every response carries your live counters, so a client can back off before hitting a wall:
| Header | Meaning |
|---|---|
X-Quota-Daily-Limit / -Remaining | Daily allowance and what's left |
X-Quota-Monthly-Limit / -Remaining | Monthly allowance and what's left |
Retry-After | Seconds until the exhausted window resets (on a 429) |
X-Data-Freshness | The day the dataset last changed (YYYY-MM-DD) |
X-Request-Id | Correlation id — quote it in any support request |
When a window is exhausted the API returns 429 with
{ "error": …, "code": "quota_exceeded", "window": "daily" } and a
Retry-After header. Honor it and retry after the reset.
Errors
Errors use a consistent JSON envelope — an error message and a stable
machine-readable code:
{ "error": "API quota exceeded", "code": "quota_exceeded" }| Status | Code | Meaning |
|---|---|---|
| 401 | auth_required | Missing or invalid key |
| 403 | api_access_required | Key valid, but no active API entitlement |
| 404 | not_found | No entity matches the path parameter (e.g. /companies/{name}) |
| 429 | quota_exceeded | Daily or monthly window exhausted — see Retry-After |
| 503 | quota_unavailable | Metering temporarily unavailable — retry shortly |
| 500 | — | Unexpected server error — quote X-Request-Id to support |
X-Request-Id. Including it when you contact
support lets us pull the exact request from our logs.