Overview
SignalFx built a cloud monitoring service that processed measurements as they arrived. Engineers could see changes in infrastructure and applications, group related measurements, and receive alerts when behavior changed. Splunk acquired the company in 2019 for approximately $1.05 billion before adjustments and incorporated its technology into its observability products.[12][1]
SignalFx's approach addressed a specific change in computing: cloud applications could create and remove many short-lived services, making a fixed dashboard of servers less useful. Streaming analysis helped teams inspect those changing systems, but the company also faced competitors building broader monitoring suites.
Founding Story
Karthik Rau and Phillip Liu founded the company in 2013 as SignalFuse. They had worked together at Loudcloud, later known as Opsware. Rau subsequently worked on VMware's management products; Liu worked on monitoring infrastructure at Facebook. Their experience connected two operational problems: managing distributed systems and making sense of the measurements those systems produce.[2][3]
SignalFx began selling in 2015. Its early product emphasized streaming operational data rather than waiting for a batch report. This mattered to engineers trying to diagnose a fast-moving incident, though the available evidence does not isolate how much faster incident resolution became for customers.[4]
Timeline
- 2013: Rau and Liu establish the company as SignalFuse.[2]
- 2015: SignalFx starts sales; a16z describes its investment in the company.[3][4]
- 2018: SignalFx raises $45 million in Series D financing, including participation from a16z.[5]
- 2019: It raises a $75 million Series E and Splunk completes its acquisition on October 1 for approximately $1.05 billion before adjustments.[12][4][1]
What They Built
A customer connected cloud infrastructure and applications to SignalFx. The service collected metrics, which are measurements such as request counts, latency, or resource use over time. Its streaming system analyzed incoming measurements and made them available for charts and alerts within seconds, according to company and Splunk material.[4][6]
The distinction from a static dashboard is continuous computation. An engineer could group related measurements, apply a calculation, and monitor the result as new points arrived. SignalFlow, the analytics language that continued in Splunk Infrastructure Monitoring, provided one way to query that stream.[7]
SignalFx later added monitoring for applications built from microservices. The company said its NoSample architecture observed every transaction rather than selecting a random sample. That was a company description of the product; the sources reviewed do not independently verify its coverage for every customer.[4]
Market Position
Target Customers
SignalFx targeted engineering and operations teams running cloud infrastructure. In 2019 it named customers including HubSpot, Kayak, Square, Yelp, Amtrak, and NBCUniversal. Those names show reported adoption across both newer cloud companies and established enterprises; they do not reveal contract value or retention.[4]
Market Size
The company sold into cloud infrastructure and application monitoring. A reliable estimate for the particular market it could serve at the time was not established.
Competition
Datadog and Splunk competed to bring metrics, events, and logs into broader operational tools. A customer choosing SignalFx gained a streaming monitoring system but still had to consider how it would connect with other tools used during an incident. Splunk later combined SignalFx's metrics work with its own wider portfolio.[8][1]
Business Model
SignalFx sold hosted monitoring software. Its 2019 financing announcement reported customers and revenue growth but did not disclose revenue, gross margin, or average contract value. One contemporaneous user described pricing tied to data volume and the number of distinct metric series; that account is useful as a single customer's experience, not a company-wide price schedule.[4][9]
Traction
SignalFx said its annual revenues grew at a 170% compound annual rate from the beginning of sales in 2015 to 2019. It also reported hundreds of customers and 270 employees in June 2019. The growth rate does not reveal the starting revenue or profitability.[4]
Outcome and evolution
Metrics complemented Splunk's existing tools
Splunk said SignalFx added real-time metrics and monitoring for cloud infrastructure and applications. For Splunk, the acquisition joined SignalFx's streaming work with an existing business in machine-generated data. The structural fit was that engineers often need several kinds of evidence during one incident: a metric can show when performance changed, while related logs or traces can help explain why.[1]
The alternative explanation is that Splunk primarily valued access to SignalFx's team or customers. The announcement supports the product rationale but does not quantify each asset's contribution to the price. No evidence here supports treating the transaction as a distressed shutdown.
The product continued under another name
Splunk's current Observability Cloud offers infrastructure monitoring with streaming analytics, dashboards, and OpenTelemetry ingestion. Its 2026 domain transition documentation explicitly maps older SignalFx addresses to newer Observability Cloud addresses. The original company no longer operates independently, while its product lineage remains visible in the successor.[10][11]
Key Lessons
- Make the data timely enough for the job. SignalFx processed metrics as they arrived because cloud incidents can change before a batch report is ready.
- Separate measurements from diagnosis. Charts and alerts identify changes; an engineer still needs context from other evidence to determine a cause.
- Treat broad distribution as part of the product. SignalFx sold to both cloud-native and established companies before joining a larger monitoring vendor.
- Check the successor before rebuilding. Streaming analytics and SignalFlow survived inside Splunk; a new product must find a narrower unmet workflow.
Sources
- Splunk, SignalFx acquisition
- CRN, SignalFuse founding
- a16z, systems management
- SignalFx, 2019 financing
- SignalFx, Series D
- Splunk, streaming architecture
- Splunk, SignalFlow
- TechTarget, monitoring competition
- Reddit, one operator's experience
- Splunk, current pricing
- Splunk, domain transition
- Splunk, acquisition filing