{ "openapi": "3.1.1", "info": { "title": "CSV/Excel Chart Studio API", "version": "1.0.0", "summary": "Turn CSV, TSV or Excel data into line, bar, pie, scatter or histogram charts with SVG/PNG export.", "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://csvexcelchartstudio.usefulweb.site" } ], "paths": { "/api/v1/calculate": { "post": { "operationId": "calculate", "summary": "Turn CSV, TSV or Excel data into line, bar, pie, scatter or histogram charts with SVG/PNG export.", "description": "Upload a CSV, TSV or XLSX file (up to 20 MB) or paste a table. The studio detects numbers, dates and categories, lets you pick the chart type, X/Y columns, a grouping column, aggregation (sum, average, count …), sorting and top-N, and returns an accessible SVG chart with SVG and PNG downloads plus the data table behind it.\n\nMethodology:\n- The upload is identified by its content: XLSX (a ZIP container) is unpacked with a built-in reader (shared strings, number formats for dates, cached formula values of the chosen sheet); everything else is read as UTF-8 text (Windows-1252 as fallback) and split with the delimiter that gives the most consistent column count.\n- Each column is classified as number, date or text when at least 90 % of its non-empty cells parse that way. Numbers may use thousands separators, a decimal comma (detected per column), currency signs, percent signs and (123) for negatives. Day/month order of dates like 03/04/2026 is detected per column; when the data never disambiguates it, day-first is assumed and stated.\n- For bar, stacked, pie, line and area charts, rows with the same X value are combined with the chosen aggregation (automatic = sum). With a group column, the first Y column is split into one series per group value (at most 8; the rest become \"Other\"). Top N keeps the categories with the largest totals.\n- Charts are drawn by the site’s own SVG library: colour-blind-safe Okabe–Ito colours plus dash patterns or marker shapes, a text alternative, and the data table below. PNG images are rendered from the same SVG at 2× resolution with ImageMagick.\n- Very large inputs are reduced for drawing only: lines with more than 2,000 points show bucket averages, scatter plots with more than 5,000 points show every n-th point; the table and CSV keep all values.\n\nCheck that the detected column types and the aggregation match your data before publishing a chart.", "tags": [ "charts" ], "x-mcp-tool": "csv_excel_chart_studio", "requestBody": { "required": true, "content": { "application/json": { "schema": { "$ref": "#/components/schemas/CsvExcelChartStudioInput" }, "examples": { "example1": { "summary": "Revenue by month, stacked by region", "value": { "data": "Month,Region,Revenue,Orders\n2026-01,North,12400,310\n2026-01,South,9800,250\n2026-02,North,13900,342\n2026-02,South,10150,262\n2026-03,North,15100,371\n2026-03,South,11800,290\n2026-04,North,14650,355\n2026-04,South,12900,301", "chartType": "stacked", "x": "Month", "y": "Revenue", "group": "Region", "png": false } }, "example2": { "summary": "Monthly orders as a line (repeated months summed)", "value": { "data": "Month,Region,Revenue,Orders\n2026-01,North,12400,310\n2026-01,South,9800,250\n2026-02,North,13900,342\n2026-02,South,10150,262\n2026-03,North,15100,371\n2026-03,South,11800,290\n2026-04,North,14650,355\n2026-04,South,12900,301", "chartType": "line", "x": "Month", "y": "Orders", "png": true } }, "example3": { "summary": "Share of revenue by region (pie)", "value": { "data": "Month,Region,Revenue,Orders\n2026-01,North,12400,310\n2026-01,South,9800,250\n2026-02,North,13900,342\n2026-02,South,10150,262\n2026-03,North,15100,371\n2026-03,South,11800,290\n2026-04,North,14650,355\n2026-04,South,12900,301", "chartType": "pie", "x": "Region", "y": "Revenue", "png": false } } } } } }, "responses": { "200": { "description": "Calculation result envelope.", "content": { "application/json": { "schema": { "$ref": "#/components/schemas/CsvExcelChartStudioResult" } } } }, "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" } } } } } }, "CsvExcelChartStudioInput": { "type": "object", "additionalProperties": false, "properties": { "file": { "title": "CSV, TSV or Excel file", "description": "CSV/TSV/TXT or .xlsx, max 20 MB. The format is detected from the content. Old .xls files: save as .xlsx first. Upload as {filename, contentType?, contentBase64}. Max 20480 KiB. Accepts .csv,.tsv,.txt,.xlsx,text/csv,text/tab-separated-values,text/plain,application/vnd.openxmlformats-officedocument.spreadsheetml.sheet.", "type": "object", "additionalProperties": false, "required": [ "filename", "contentBase64" ], "properties": { "filename": { "type": "string" }, "contentType": { "type": "string" }, "contentBase64": { "type": "string" } } }, "data": { "title": "Or paste data", "description": "Comma-, semicolon-, tab- or pipe-separated, first row = headers. Used when no file is uploaded.", "type": "string", "maxLength": 2000000 }, "sheet": { "title": "Excel sheet", "description": "Sheet name or number; default: the first sheet.", "type": "string", "maxLength": 120 }, "hasHeader": { "title": "First row contains column names", "type": "boolean", "default": true }, "chartType": { "title": "Chart type", "type": "string", "enum": [ "auto", "line", "area", "bar", "stacked", "scatter", "pie", "donut", "histogram" ], "default": "auto" }, "x": { "title": "X column (categories or dates)", "description": "Column name, letter (A, B …) or number. Empty: first date or text column.", "type": "string", "maxLength": 200 }, "y": { "title": "Y columns (values)", "description": "One or more column names, comma-separated. Empty: the numeric columns. No numeric column: rows are counted.", "type": "string", "maxLength": 1000 }, "group": { "title": "Group / series column", "description": "Optional: split the first Y column into one series per value of this column (e.g. Region) – ideal for stacked bars.", "type": "string", "maxLength": 200 }, "aggregation": { "title": "Combine repeated X values", "type": "string", "enum": [ "auto", "sum", "avg", "count", "min", "max", "median", "none" ], "default": "auto" }, "sort": { "title": "Sort", "type": "string", "enum": [ "auto", "none", "x", "value-desc", "value-asc" ], "default": "auto" }, "topN": { "title": "Top N categories", "description": "0 = all (very long category lists are cut automatically).", "type": "integer", "minimum": 0, "maximum": 200, "default": 0 }, "otherBucket": { "title": "Combine the rest into \"Other\"", "type": "boolean", "default": true }, "bins": { "title": "Histogram bins", "description": "0 = automatic (Sturges’ rule).", "type": "integer", "minimum": 0, "maximum": 100, "default": 0 }, "title": { "title": "Chart title", "type": "string", "maxLength": 140 }, "png": { "title": "Also create a PNG image", "type": "boolean", "default": true } }, "required": [] }, "CsvExcelChartStudioResult": { "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": [ "source", "columns", "chart", "table", "svg", "png" ], "properties": { "source": { "type": "object", "additionalProperties": false, "required": [ "format", "rows", "columns", "sheet", "truncated" ], "properties": { "format": { "type": "string" }, "rows": { "type": "integer" }, "columns": { "type": "integer" }, "sheet": { "type": [ "string", "null" ] }, "sheets": { "type": "array", "items": { "type": "string" } }, "delimiter": { "type": [ "string", "null" ] }, "truncated": { "type": "boolean" } } }, "columns": { "type": "array", "items": { "type": "object", "additionalProperties": false, "required": [ "name", "type", "nonEmpty", "distinct" ], "properties": { "name": { "type": "string" }, "type": { "type": "string", "enum": [ "number", "date", "category", "empty" ] }, "nonEmpty": { "type": "integer" }, "distinct": { "type": "integer" } } } }, "chart": { "type": "object", "additionalProperties": false, "required": [ "type", "title", "x", "y", "group", "aggregation", "sort", "topN", "categories", "series", "points" ], "properties": { "type": { "type": "string" }, "title": { "type": "string" }, "x": { "type": [ "string", "null" ] }, "y": { "type": "array", "items": { "type": "string" } }, "group": { "type": [ "string", "null" ] }, "aggregation": { "type": "string" }, "sort": { "type": "string" }, "topN": { "type": "integer" }, "categories": { "type": "integer" }, "series": { "type": "integer" }, "points": { "type": "integer" } } }, "table": { "type": "object", "additionalProperties": false, "required": [ "header", "rows", "totalRows" ], "properties": { "header": { "type": "array", "items": { "type": "string" } }, "rows": { "type": "array", "items": { "type": "array" } }, "totalRows": { "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" } } } } } } } }