# Log Sequence Diagram Converter Convert structured service logs into Mermaid or PlantUML sequence diagrams, with optional latency and error annotations > Canonical page: https://elysiatools.com/en/tools/log-sequence-diagram-converter - **Category:** Development - **Keywords:** logs, sequence diagram, mermaid, plantuml, service trace, microservices ## Overview Paste JSON lines or trace-style text logs, or upload a log file. The tool first parses interaction-like events such as serviceA -> serviceB or structured JSON with source / target / action fields, then generates a sequence diagram in Mermaid or PlantUML. How to use it: - Log Input / Log File: provide logs that contain cross-service interaction hints - Diagram Format: choose Mermaid or PlantUML - Include Latency Notes: adds per-step latency markers where available - Highlight Errors: annotates failing steps with error notes - Max Steps: compresses the output so the diagram stays readable Supported patterns: - JSON lines with fields like source, target, action, status, latencyMs, error - arrow logs such as api -> auth POST /login | status=401 | latency=82ms - trace-style lines such as [api] GET /users -> [db] 200 14ms Output: - compact interaction summary - Mermaid or PlantUML sequence diagram source - AI-assisted summarization when possible, with heuristic fallback when AI is unavailable ## Inputs - **Log Input** (textarea): 2026-04-06T10:00:01Z api -> auth POST /login | status=401 | latency=82ms | error=invalid token - **Log File** (file) - **Diagram Format** (select) - **Include Latency Notes** (checkbox) - **Highlight Errors** (checkbox) - **Max Steps** (number) ## When to use - When debugging failed requests across multiple microservices to pinpoint exactly where an error occurred. - When documenting system architecture and API interactions based on real production traffic logs. - When analyzing performance bottlenecks by visualizing service hops and step-by-step latency. ## How it works - Paste your structured logs (JSON lines, arrow logs, or trace-style text) or upload a .log or .jsonl file. - Select your preferred diagram format (Mermaid or PlantUML) and configure options like latency notes and error highlighting. - Set a maximum step count to compress the output and ensure the diagram remains readable. - The tool parses the source, target, and action fields to generate a compact interaction summary and the corresponding diagram source code. ## Use cases - Visualizing a complex authentication flow trace to identify a 401 Unauthorized error source. - Generating up-to-date sequence diagrams for technical documentation directly from staging environment logs. - Mapping database query latency across different backend services to find slow API endpoints. ## Frequently asked questions ### What log formats are supported? The tool supports JSON lines with source/target fields, arrow-style logs (e.g., api -> auth), and trace-style text logs. ### Can I limit the size of the generated diagram? Yes, you can set a 'Max Steps' limit (between 3 and 40) to compress the output and ensure the sequence diagram remains readable. ### How are errors displayed in the diagram? If you enable 'Highlight Errors', the tool annotates failing steps with specific error notes directly on the sequence diagram. ### Does it support PlantUML? Yes, you can choose between Mermaid and PlantUML as your output diagram format. ### Can I upload a log file instead of pasting text? 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