Module Overview

Module Overview

flow8 includes 135+ built-in modules across 13 categories. Every module is auto-discovered at startup and available in flow definitions via its appId.

Module Categories

Category	Count	Examples
Control Flow	5	Router, Iterator, Aggregator, Subflow, Enumeration
Data & Utilities	20+	Var, Template, Base64, URL, Regex, Array, JSON, CSV
HTTP & Network	2	cURL, Wget
AI & Machine Learning	5	Chat, Embeddings, Structured Extract, AI Prompt, MCP Agent Loop
Storage	8+	Read, Write, Move, Delete, Exists, List, TempDir, S3, GCS, Drive
Database	9+	Query, Insert, Update, Delete, Upsert, Search, Raw, F8DB
Email & Messaging	4	Send Mail (SMTP), IMAP, POP3, Slack
Document Processing	8+	PDF Extract, PDF Merge, PDF Split, HTML→PDF, OCR, ImageMagick, DOCX
Cryptography	3	AES-GCM, HMAC-SHA256, JWT
Generators	5	UUID, CUID2, Random, Now, Currency Rates
Key-Value Store	3	KV Get, KV Set, KV Append
External Integrations	20+	Clio, QuickBooks, Bexio, Microsoft Graph, Google Sheets
Debug & Testing	8	Args log, Success, Failed, Sleep, Repeat, WatchDog, Code exec

Finding a Module

Browse modules via the API:

GET /api/apps
GET /api/apps?category=ai
GET /api/apps?search=pdf

Or generate the full catalog as CSV:

go run cmd/modulescsv/main.go

Module Structure in a Flowlet

Every module is referenced in a flowlet via its appId:

{
  "appId": "curl",
  "ref": "myStep",
  "args": {
    "method": "GET",
    "url": "https://api.example.com/data"
  }
}

Module Versioning

Modules have a version number. When a module’s argument schema changes, existing flowlets referencing the old version are automatically migrated by the ModuleMigrationService at startup. The moduleVersion field in each flowlet records which schema version it was last migrated to.

Module Output

Every module returns an out map accessible in downstream expressions via the step’s ref name:

{{ $prev.<ref>.<outputField> }}

Check the OutExample() of each module (visible in the API response for /api/apps/{id}) to see what fields are returned.