Transloadit

REST API at api2.transloadit.com. POST /assemblies creates a new processing job with params (JSON assembly definition). GET /assemblies/{id} polls status. Assembly params include steps (robot definitions) and template_id (for reusing saved pipeline configs). Each step specifies a robot (/image/resize, /video/encode, etc.) and its parameters (width, height, format, bitrate, etc.). Results include final URLs for all processed files. Server-sent notifications available in addition to webhook.

Assembly status includes detailed step-by-step results. Error in any step surfaces with error type, message, and the file that failed. Failed assemblies include partial results for successful steps. Rate limits per account plan (parallel assembly limits). Transloadit SLA: 99.9% uptime. Processing queue depth visible in account dashboard. Assembly timeout configurable (default: 24h). Webhook delivers final status; polling is also supported.

Transloadit processes files through 'assemblies' — JSON-defined pipelines of sequential transformation steps using specialized 'robots' (e.g., /image/resize, /video/encode, /audio/transcode, /document/convert). For agents, the assembly pattern is powerful for media pipeline automation: ingest files from URLs or S3, transform through multiple steps (resize → watermark → compress), and export to S3/GCS/Cloudinary/any URL. Assembly creation returns an assembly_id for status polling; webhook delivers results when complete. Over 100 robots cover most media processing needs. HMAC-SHA1 auth is more complex than API key but prevents request tampering. Confidence is docs-derived.

HMAC-SHA1 auth: each request signed by hashing the assembly params with the secret key and including the signature and auth_key in the request. More complex than simple API key headers but prevents tampering and replay attacks. Auth key and secret from Transloadit account settings. No OAuth2. Template-based requests can simplify auth surface by moving sensitive config to server-side templates. HTTPS enforced.

transloadit.com/docs provides comprehensive documentation: getting started guide, all robot references (100+ robots with full parameter docs), template management, webhook setup, SDK guides (Node.js, Python, PHP, Ruby, iOS, Android), and the REST API reference. Robot documentation is particularly thorough with examples for every transformation param. Getting started requires an account (free plan with monthly credit). Community support via email and GitHub issues.