MarginKit

The problem

An agency quotes a fixed price for an n8n automation. The workflow ships, and then an AI agent with maxIterations: 100 meets a tool that returns malformed JSON. It retries. The client's API bill arrives, and the margin on that project is gone.

The failure is not exotic — unbounded agents, AI nodes inside loops, chained retries and hard-coded keys are all visible in the export file. The problem is that nobody reads a 26-node JSON export looking for them before signing.

What it does

MarginKit reads an n8n export and reports what it will cost and where it will break — as a browser analyzer or a Python CLI.

• Per-node AI cost as honest ranges. Low, typical and high — never a fake single number. 83 models priced across OpenAI, Anthropic, Google, DeepSeek, Mistral, Grok, Llama and others, including OpenRouter-style ids, with the pricing snapshot date shown on the report.
• Real loop detection. Actual cycle detection in the workflow graph, not keyword guessing. An AI node inside a loop multiplies its cost per iteration, and MarginKit says by how much.
• Unbounded agent detection. Flags agents with no iteration budget, budgets above 10, and every agent tool with no error path — the documented trigger of runaway billing.
• Retry storm arithmetic. Three nodes at five tries each is up to 125 paid calls for one run. It computes that chain.
• Things that damage the client. A key typed into a node instead of the credential store travels inside the export you email. A retry on a send delivers the message twice. MarginKit reports where a secret is, never what it is.
• Workflow Fixer. Prepares an explicit plan, shows the diff, and requires confirmation for any change that alters execution or cost.
• Client quote generator. On the Agency tier: estimated monthly cost, recommended price to bill, resulting margin and the optimisations that justify it, exported as a branded document.

The workflow is analyzed entirely in your browser or on your machine. It is never uploaded.

Who it is for

Agencies and freelancers who deliver n8n AI workflows on fixed-price contracts, and who carry the API bill if the estimate was wrong. The free browser analyzer is also useful to anyone inheriting a workflow they did not write.