v0.1 alpha · open source · Spring Boot + React
Causeline traces a user action from the React click, through your Spring Boot controllers, services and SQL, out to the APIs you call, and back to the state update. One timeline. Then replay the request and compare the two runs.
POST /charge to the payment provider spends 812 ms of its own time, 75% of the trace. Your code is fine; the provider is slow.Finding out why means stitching together five tools that have never heard of each other. Each shows one layer. None shows the cause.
The click, the request, the controller, your @Observed services, Spring Data repositories, every SQL statement with its real values, outbound HTTP calls, the state update and the re-render, as one tree.Browser and server clocks are lined up by the span tree, not by wall time.
The slowest operation is flagged by self time, so a slow parent doesn't hide the real culprit. Repeated queries (N+1) and exceptions are called out too, including the ones your code catches and only logs.Exceptions point to the file and line in your code that threw.
Send a captured request again, to local, dev or QA, with that environment's credentials. Then compare the two runs span by span to see exactly what changed after your fix.POST, PUT and DELETE ask for confirmation first.
Headers, request and response bodies and SQL values are shown in full while you debug, because hidden data slows you down. Anything that leaves the app, like an OTLP export or a shared trace file, is redacted.Block any header, field or query key with one setting.
Causeline builds on W3C Trace Context, Micrometer and OpenTelemetry, so it fits the way Spring Boot already observes your app.
@causeline/react wraps fetch and XHR, names the click with trace(), and adds a traceparent header to your own API calls.
The starter picks up the header. HTTP handling, controllers, services, repositories, JDBC and outbound clients become spans in the same trace.
/causelineSpans from both sides land in an in-memory store inside your app. Open /causeline and the whole action is there, on one timeline.
traceparent: 00-4bf92f3577b34da6a3ce929d0e0e4736-00f067aa0ba902b7-01 trace id · parent span · sampled
No account, no agent, no cloud. Causeline runs inside your Spring Boot app, is off until you switch it on in a dev profile, and refuses to start under a production profile.
Spring Boot 4.1 with Java 21+, and React 18+. Published on Maven Central and npm.
<dependency> <groupId>dev.causeline</groupId> <artifactId>causeline-spring-boot</artifactId> <version>0.1.0-alpha.0</version> </dependency>
implementation("dev.causeline:causeline-spring-boot:0.1.0-alpha.0")
npm install @causeline/react
# Only in a dev or QA profile causeline: enabled: true
One dependency. No agent, no extra process.
causeline.enabled: true. It stays off everywhere else.
<CauselineProvider endpoint="/causeline/api/spans">, then name actions with trace('Checkout', …).
The log prints a Causeline UI: link with an access token. Your click is waiting there.
No, and it makes sure of that. Causeline is for development and QA. It is off unless causeline.enabled is true, and it refuses to start when a prod or production profile is active, because it shows headers, cookies and bodies in full.
No. Causeline runs inside your Spring Boot application and serves its UI at /causeline. There is no account, no cloud service and no separate process to run.
Spring Boot 4.1 with Spring MVC on Java 21 or newer, and React 18 or newer. WebFlux is not supported yet.
Yes. It propagates the W3C traceparent header and is built on Micrometer Observation and OpenTelemetry. It can also export redacted spans over OTLP to Jaeger, Grafana Tempo or an OpenTelemetry Collector.
By default it records headers, query strings, request and response bodies, SQL with bound values and exception details, and shows them only in your local UI. Any of it can be blocked with causeline.capture.* settings or the React capture prop, and anything exported is redacted.
Yes. Causeline is open source under the Apache License 2.0. The code, issues and roadmap are on GitHub.
Senior Full Stack & AI Engineer · Bengaluru, India
Sudharma has spent more than five years building backend systems with Spring Boot and front ends with React, along with RAG pipelines and LLM-based platforms. Causeline is built for exactly that kind of work: following a request across React and Spring Boot without switching between five tools.
Using Causeline, or want to help shape it? Say hello on LinkedIn or open an issue.