> ## Documentation Index > Fetch the complete documentation index at: https://docs.linqalpha.com/llms.txt > Use this file to discover all available pages before exploring further. # Get Upload URL > Returns a presigned S3 PUT URL for direct file upload. Lets clients upload files without managing AWS credentials or staging buckets — the server signs a single-use URL bound to a server-generated S3 object key, the client PUTs the file body to that URL, then registers the upload via `POST /v1/sources` with the returned `file_key`. **Why this exists:** `POST /v1/sources` requires a `file_key` for an object that already exists in our backing storage. Customers without their own staging bucket use this endpoint to obtain an upload URL pointed at the canonical destination directly, eliminating any client-side AWS setup. **Important — Content-Type binding:** The presigned URL is signed with `Content-Type` baked into the signature. The client **MUST** send a matching `Content-Type` header on the PUT request, otherwise S3 rejects with HTTP 403 (`SignatureDoesNotMatch`). The expected value is returned in the `content_type` field of this response — pass it back as the `Content-Type` header on your PUT. **Workflow:** 1. Create a source batch via `POST /v1/source_batches` (returns `source_batch_id`) 2. Call this endpoint with `name`, `source_type`, `source_batch_id` (returns `upload_url`, `file_key`, `content_type`, `expires_in`) 3. PUT the file to `upload_url` with `Content-Type: ` header 4. Register the source via `POST /v1/sources` with `file_key` from step 2 5. Poll `GET /v1/sources/{source_id}` until `status: "success"` 6. Reference `source_batch_id` in chat/search requests **Constraints:** - Supported `source_type`: `pdf`, `docx`, `xlsx`, `pptx`, `doc`, `txt` - Maximum file size enforced at registration step: 20MB - Maximum 10 active sources (status: `processing` or `success`) per source_batch — `failed`/`deleted` sources do not count toward the limit (enforced when generating the URL) - URL expires after 10 minutes (`expires_in: 600`) - File is validated at registration time (`POST /v1/sources`); a wrong-content upload will be accepted by S3 but rejected when registering ## OpenAPI ````yaml POST /v1/sources/upload_url openapi: 3.0.1 info: title: LinqAlpha API description: >- Linq helps finance professionals make informed decisions using Retrieval-Augmented Generation (RAG)-enhanced answers. By leveraging cutting-edge Large Language Models (LLM) and supplementary technology, Linq provides the most optimized responses based on your queries. version: 1.0.0 license: name: MIT servers: - url: https://api.linqalpha.com security: - ApiKeyAuth: [] tags: - name: Search description: Search and generate responses - name: Data description: Data retrieval and mapping - name: Feedback description: Conversation feedback - name: RMS description: Research Management System - name: Source Management description: Source batch and file management - name: MCP description: >- LinqAlpha MCP — Financial data tools for AI assistants via Model Context Protocol - name: Connectors description: Customer Connectors — customer-owned MCP connector management - name: Briefing description: Briefing Agent — automated market briefings with scheduling and delivery - name: Status description: Sync status — check organization, document, and container sync progress paths: /v1/sources/upload_url: post: tags: - Source Management summary: Get Upload URL description: >- Returns a presigned S3 PUT URL for direct file upload. Lets clients upload files without managing AWS credentials or staging buckets — the server signs a single-use URL bound to a server-generated S3 object key, the client PUTs the file body to that URL, then registers the upload via `POST /v1/sources` with the returned `file_key`. **Why this exists:** `POST /v1/sources` requires a `file_key` for an object that already exists in our backing storage. Customers without their own staging bucket use this endpoint to obtain an upload URL pointed at the canonical destination directly, eliminating any client-side AWS setup. **Important — Content-Type binding:** The presigned URL is signed with `Content-Type` baked into the signature. The client **MUST** send a matching `Content-Type` header on the PUT request, otherwise S3 rejects with HTTP 403 (`SignatureDoesNotMatch`). The expected value is returned in the `content_type` field of this response — pass it back as the `Content-Type` header on your PUT. **Workflow:** 1. Create a source batch via `POST /v1/source_batches` (returns `source_batch_id`) 2. Call this endpoint with `name`, `source_type`, `source_batch_id` (returns `upload_url`, `file_key`, `content_type`, `expires_in`) 3. PUT the file to `upload_url` with `Content-Type: ` header 4. Register the source via `POST /v1/sources` with `file_key` from step 2 5. Poll `GET /v1/sources/{source_id}` until `status: "success"` 6. Reference `source_batch_id` in chat/search requests **Constraints:** - Supported `source_type`: `pdf`, `docx`, `xlsx`, `pptx`, `doc`, `txt` - Maximum file size enforced at registration step: 20MB - Maximum 10 active sources (status: `processing` or `success`) per source_batch — `failed`/`deleted` sources do not count toward the limit (enforced when generating the URL) - URL expires after 10 minutes (`expires_in: 600`) - File is validated at registration time (`POST /v1/sources`); a wrong-content upload will be accepted by S3 but rejected when registering requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/UploadUrlRequest' example: name: Q4_Revenue_Report.pdf source_type: pdf source_batch_id: 123e4567-e89b-12d3-a456-426614174000 responses: '200': description: Presigned upload URL generated content: application/json: schema: $ref: '#/components/schemas/UploadUrlResponse' example: upload_url: >- https://linq-vertex-documents.s3.amazonaws.com/uploads/1715000000000_a1b2c3d4_Q4_Revenue_Report.pdf/original.pdf?X-Amz-Algorithm=...&X-Amz-Signature=... file_key: >- uploads/1715000000000_a1b2c3d4_Q4_Revenue_Report.pdf/original.pdf content_type: application/pdf expires_in: 600 '400': description: Bad request — invalid `source_type` or missing required fields '401': description: Unauthorized — invalid or missing API key '404': description: Source batch not found or not accessible to the caller '422': description: Source batch already contains the maximum number of sources (10) components: schemas: UploadUrlRequest: type: object properties: name: type: string description: >- Display name for the source, typically the original filename. Used to construct the S3 object key. example: Q4_Revenue_Report.pdf source_type: type: string description: >- File extension. Determines the expected `Content-Type` baked into the presigned URL signature. enum: - pdf - docx - xlsx - pptx - doc - txt example: pdf source_batch_id: type: string format: uuid description: >- Source batch the upload will be registered under. Must be created first via `POST /v1/source_batches`. Per-batch source limit (10) is enforced here. example: 123e4567-e89b-12d3-a456-426614174000 required: - name - source_type - source_batch_id UploadUrlResponse: type: object properties: upload_url: type: string format: uri description: >- Presigned S3 PUT URL. Single-use, signed with the `content_type` value below. Send the file body via `PUT ` with header `Content-Type: `. example: >- https://linq-vertex-documents.s3.amazonaws.com/uploads/1715000000000_a1b2c3d4_Q4_Revenue_Report.pdf/original.pdf?X-Amz-Algorithm=...&X-Amz-Signature=... file_key: type: string description: >- Server-generated object key. Pass this as `file_key` in the subsequent `POST /v1/sources` call to register the uploaded file. example: uploads/1715000000000_a1b2c3d4_Q4_Revenue_Report.pdf/original.pdf content_type: type: string description: >- Content-Type baked into the presigned URL signature. Client MUST send this exact value as the `Content-Type` header on the PUT, otherwise S3 rejects with HTTP 403 (`SignatureDoesNotMatch`). example: application/pdf expires_in: type: integer description: Seconds until `upload_url` expires. After this, request a new URL. example: 600 required: - upload_url - file_key - content_type - expires_in securitySchemes: ApiKeyAuth: type: apiKey in: header name: X-API-KEY ````