{ "openapi": "3.1.1", "info": { "title": "Diagram & Flowchart Maker API", "version": "1.0.0", "summary": "Write flowcharts, sequence diagrams and mind maps as text and get a laid-out SVG/PNG diagram.", "description": "Every endpoint performs the same calculation as the human page and returns inputs, result, units, assumptions, sources, warnings and computedAt. MCP endpoint: /mcp." }, "servers": [ { "url": "https://diagramflowchartmaker.usefulweb.site" } ], "paths": { "/api/v1/calculate": { "post": { "operationId": "calculate", "summary": "Write flowcharts, sequence diagrams and mind maps as text and get a laid-out SVG/PNG diagram.", "description": "Type a diagram in a Mermaid-like text syntax – flowcharts (top-down or left-right, node shapes, labelled arrows), sequence diagrams (participants, messages, notes, loop/alt blocks) or indented mind maps – and get an automatically laid-out, accessible SVG with SVG/PNG downloads. Syntax errors are reported with line numbers.\n\nMethodology:\n- The text is parsed line by line; every error is reported with its line (and column for flowcharts). Supported: flowchart/graph TD|TB|BT|LR|RL with shapes [rect] (round) ([stadium]) [[subroutine]] [(database)] ((circle)) {diamond} {{hexagon}} [/parallelogram/] [/trapezoid\\] >flag], arrows --> --- -.-> ==> <-->, labels -->|text| or -- text -->, chains A --> B --> C and groups A & B --> C; sequenceDiagram with participant/actor (… as Alias), ->> -->> -> --> -x --x -) --), Note left of/right of/over, loop/alt/else/opt/par/critical/break … end, autonumber; mindmap with indentation and the usual node shapes.\n- Flowcharts are laid out with a layered (Sugiyama-style) algorithm: cycles are broken by reversing DFS back edges; nodes get the longest-path layer (edges with labels span two layers so the label gets its own slot); long edges get dummy nodes; crossings are reduced with 24 alternating barycentre sweeps plus adjacent swaps, keeping the best ordering; positions are assigned by order-preserving least squares (isotonic regression) toward the neighbours, which keeps long edges straight.\n- Sequence diagrams place participants in order of appearance, widen gaps to fit message texts and stack messages, notes and blocks top-down. Mind maps are drawn as a two-sided tree, balancing first-level branches by their number of leaves.\n- Styling statements (style, classDef, class, linkStyle, click) and subgraph frames are accepted but not drawn; they are listed as ignored lines. The output is plain SVG (no scripts, no external references) that passes the site’s strict sanitiser; arrowheads are drawn as shapes so PNG export keeps them.\n\nA Mermaid-like subset, not full Mermaid compatibility: complex features (subgraph frames, styling, class diagrams, Gantt charts) are not supported.", "tags": [ "charts" ], "x-mcp-tool": "diagram_flowchart_maker", "requestBody": { "required": true, "content": { "application/json": { "schema": { "$ref": "#/components/schemas/DiagramFlowchartMakerInput" }, "examples": { "example1": { "summary": "Order flowchart (top-down, shapes, labelled edges, a loop)", "value": { "source": "flowchart TD\n start([Order received]) --> pay{Paid?}\n pay -->|Yes| pick[Pick items]\n pay -->|No| remind[/Send reminder/]\n remind --> pay\n pick --> stock{In stock?}\n stock -->|Yes| ship[[Ship parcel]]\n stock -->|No| back[(Backorder list)]\n back -.-> pick\n ship --> done((Done))", "title": "Order handling" } }, "example2": { "summary": "Login sequence diagram", "value": { "source": "sequenceDiagram\n autonumber\n actor U as User\n participant B as Browser\n participant S as Server\n U->>B: Click \"Log in\"\n B->>S: POST /login\n alt credentials valid\n S-->>B: 303 + session cookie\n B-->>U: Dashboard\n else invalid\n S-->>B: 401 error\n Note right of B: show message\n end", "title": "Login", "png": false } }, "example3": { "summary": "Trip mind map", "value": { "source": "mindmap\n root((Trip to Lisbon))\n Travel\n Flights\n Airport transfer\n Stay\n Hotel near Baixa\n See\n Belém tower\n Tram 28\n Sintra day trip\n Eat\n Pastéis de nata", "png": false } }, "example4": { "summary": "Left-to-right pipeline", "value": { "source": "flowchart LR\n A[Commit] --> B[Build] --> C{Tests pass?}\n C -- yes --> D[Deploy]\n C -- no --> E[Notify] --> A", "png": false } } } } } }, "responses": { "200": { "description": "Calculation result envelope.", "content": { "application/json": { "schema": { "$ref": "#/components/schemas/DiagramFlowchartMakerResult" } } } }, "400": { "description": "Malformed JSON body.", "content": { "application/problem+json": { "schema": { "$ref": "#/components/schemas/Problem" } } } }, "422": { "description": "Invalid input (see errors[]).", "content": { "application/problem+json": { "schema": { "$ref": "#/components/schemas/Problem" } } } }, "429": { "description": "Rate limit exceeded (see Retry-After).", "content": { "application/problem+json": { "schema": { "$ref": "#/components/schemas/Problem" } } } } } } }, "/api/v1/tool": { "get": { "operationId": "getToolDefinition", "summary": "Inputs, output schema and examples for this tool", "responses": { "200": { "description": "Tool definition.", "content": { "application/json": { "schema": { "type": "object" } } } } } } } }, "components": { "schemas": { "Problem": { "type": "object", "description": "RFC 9457 problem details. 422 responses include per-field `errors`.", "required": [ "type", "title", "status", "detail" ], "properties": { "type": { "type": "string" }, "title": { "type": "string" }, "status": { "type": "integer" }, "detail": { "type": "string" }, "code": { "type": "string" }, "errors": { "type": "array", "items": { "type": "object", "required": [ "field", "message" ], "properties": { "field": { "type": "string" }, "message": { "type": "string" } } } } } }, "DiagramFlowchartMakerInput": { "type": "object", "additionalProperties": false, "properties": { "source": { "title": "Diagram text", "description": "First line: \"flowchart TD\" (or LR, BT, RL), \"sequenceDiagram\" or \"mindmap\". See the examples.", "type": "string", "maxLength": 50000, "default": "flowchart TD\n start([Order received]) --> pay{Paid?}\n pay -->|Yes| pick[Pick items]\n pay -->|No| remind[/Send reminder/]\n remind --> pay\n pick --> stock{In stock?}\n stock -->|Yes| ship[[Ship parcel]]\n stock -->|No| back[(Backorder list)]\n back -.-> pick\n ship --> done((Done))" }, "title": { "title": "Title", "description": "Shown above the diagram and used as its accessible name.", "type": "string", "maxLength": 140 }, "png": { "title": "Also create a PNG image", "type": "boolean", "default": true } }, "required": [ "source" ] }, "DiagramFlowchartMakerResult": { "type": "object", "additionalProperties": false, "required": [ "schemaVersion", "tool", "computedAt", "inputs", "summary", "result", "units", "assumptions", "sources", "warnings", "presentation", "links" ], "properties": { "schemaVersion": { "type": "string", "const": "1.0" }, "tool": { "type": "object", "additionalProperties": false, "required": [ "id", "name", "version" ], "properties": { "id": { "type": "string" }, "name": { "type": "string" }, "version": { "type": "string" } } }, "computedAt": { "type": "string", "format": "date-time" }, "inputs": { "type": "object", "description": "Normalised inputs actually used, including applied defaults." }, "summary": { "type": "string" }, "result": { "type": "object", "additionalProperties": false, "required": [ "kind", "title", "width", "height", "nodes", "edges", "ignoredLines", "layout", "svg", "png" ], "properties": { "kind": { "type": "string", "enum": [ "flowchart", "sequence", "mindmap" ] }, "title": { "type": "string" }, "direction": { "type": "string" }, "width": { "type": "integer" }, "height": { "type": "integer" }, "nodes": { "type": "array", "items": { "type": "object", "additionalProperties": false, "required": [ "id", "label" ], "properties": { "id": { "type": "string" }, "label": { "type": "string" }, "shape": { "type": "string" }, "depth": { "type": "integer" } } } }, "edges": { "type": "array", "items": { "type": "object", "additionalProperties": false, "required": [ "from", "to", "label" ], "properties": { "from": { "type": "string" }, "to": { "type": "string" }, "label": { "type": "string" }, "style": { "type": "string" } } } }, "ignoredLines": { "type": "array", "items": { "type": "object", "additionalProperties": false, "required": [ "line", "text" ], "properties": { "line": { "type": "integer" }, "text": { "type": "string" } } } }, "layout": { "type": [ "object", "null" ], "additionalProperties": false, "properties": { "layers": { "type": "integer" }, "crossings": { "type": "integer" }, "reversedEdges": { "type": "integer" }, "dummyNodes": { "type": "integer" } } }, "svg": { "type": "object", "additionalProperties": false, "required": [ "artifactId", "filename", "mime", "bytes", "sha256", "path" ], "properties": { "artifactId": { "type": "string" }, "filename": { "type": "string" }, "mime": { "type": "string" }, "bytes": { "type": "integer" }, "sha256": { "type": "string" }, "path": { "type": "string", "description": "Download path on the same site (valid for about 2 hours)." } } }, "png": { "anyOf": [ { "type": "object", "additionalProperties": false, "required": [ "artifactId", "filename", "mime", "bytes", "sha256", "path" ], "properties": { "artifactId": { "type": "string" }, "filename": { "type": "string" }, "mime": { "type": "string" }, "bytes": { "type": "integer" }, "sha256": { "type": "string" }, "path": { "type": "string", "description": "Download path on the same site (valid for about 2 hours)." } } }, { "type": "null" } ] } } }, "units": { "type": "object", "additionalProperties": { "type": "string" } }, "assumptions": { "type": "array", "items": { "type": "string" } }, "sources": { "type": "array", "items": { "type": "object", "additionalProperties": false, "required": [ "title" ], "properties": { "title": { "type": "string" }, "url": { "type": "string" }, "publisher": { "type": "string" }, "retrievedAt": { "type": "string" }, "note": { "type": "string" } } } }, "warnings": { "type": "array", "items": { "type": "string" } }, "presentation": { "type": "array", "items": { "type": "object" }, "description": "Display blocks used by the human page (same data)." }, "links": { "type": "object", "additionalProperties": false, "required": [ "human", "api", "openapi", "methodology" ], "properties": { "human": { "type": "string", "format": "uri" }, "api": { "type": "string", "format": "uri" }, "openapi": { "type": "string", "format": "uri" }, "methodology": { "type": "string", "format": "uri" } } } } } } } }