OLD
SaaS APIs
Predictable, Per-Call Cost
API calls have fixed, predictable costs. Payload size barely affects price.
Billed by the Request
The billable event is the API call itself.
AI Accounting InfrastructureStringCost:
StringCost:
Cloudflare meets SAP for AI.
Think Cloudflare for AI Accounting—we sit in front of your API and automatically calculate per-user, per-agent, per-outcome costs.
Revenue-firstAudit-readyAgent-native
Andreessen Horowitz just declared:
“AI is driving a shift towards outcome-based pricing. Software is becoming labor.”
But where is the infrastructure for outcome-based billing & accounting?
This is not a payments problem—it's an accounting problem. The future is outcome-based, but the tools to build it don't exist.
Until now.
The Root Cause: A New Cost Paradigm
Why is monetizing AI agents so difficult? Because the financial models that powered the last decade of SaaS are fundamentally broken in the world of Generative AI.
VS
NEW
Agentic APIs
Variable, Computational Cost
An agent's cost is tied to the work it performs—a metered computational resource, not a fixed endpoint.
Billed by the Computation
Billable events include input tokens, output tokens, reasoning steps, and every downstream tool call.
This creates a massive accounting problem traditional billing can't solve. Pricing variable, multi-step agent workflows like simple API calls forces you to guess—consistently underbill or overcharge—or build brittle accounting systems from scratch.
The Double-Entry Ledger for AI Agent Operations
Simple token counters and API proxies are failing. They see the token count and total bill from your model provider, but they can't tell you the profitability of a single agent run.
Deep Runtime Inspection
StringCost isn't a library that invades your code—it's a runtime-aware control plane that inspects your agent's traffic at the network level via a secure, signed-URL architecture. Requests flow through an asynchronous deep prompt inspection engine that classifies business intent with zero added latency.
+
Every Action is a Ledger Entry
Our sidecar and asynchronous classifier record every computational action—LLM calls, tool invocations—as a distinct line item with two sides:
- Cost Side (Debits): Tokens paid to your provider, tool call costs, compute time.
- Revenue Side (Credits): The billable event for your customer based on your pricing model.
The result: an auditable, real-time P&L for every agent run. Finally answer: “Which agents are most profitable?” “Which tools drive the most cost?” “What's our true AI margin?”
One Financial Endpoint for Your Entire AI Stack
Zero-time integration. No SDK. 250+ providers, one API.
OpenAI, Anthropic, Gemini, Cohere, Groq, and hundreds more—through a single, OpenAI-compatible proxy.
Double-Entry Accounting
A True Ledger, Not Just a Token Counter
Your AI bill is a black box. StringCost gives you X-ray vision.
While other proxies just count total tokens, we provide a double-entry ledger for every agent run. Our asynchronous background worker inspects every prompt to give you a true P&L statement for your AI.
Zero-Latency Accounting
Our Event Collector logs events instantly and returns responses with zero delay.
Asynchronous Classification
A background Worker polls every 200ms, calling a meta-classifier to tag each request with an action_type: synthesis, tool_selection, evaluation, etc.
Know Your “Why”
Finally answer critical questions: What's the P&L of your Tree-of-Thought agent? Are evaluation steps costing more than synthesis? StringCost tells you.
Security First
Unbreakable Security: No More Static API Keys
Stop embedding sk-xxx keys in your code. Our dynamic, signed-URL model makes key leakage impossible.
1
Request a One-Time URL
Your app asks the Control Plane for permission to make a call.
2
Get a Signed URL
The Control Plane returns a short-lived, single-use signed URL with encrypted credentials.
3
Call the Gateway
Your agent calls the Gateway with this URL. We validate the signature, check for replay attacks, and proxy the call.
The Enterprise Feature You've Been Waiting For: “Bring Your Own Key” (BYOK)
Stop subsidizing your customers' AI usage. Let them provide their own provider keys.
Client-Provided Keys
Let your customers enter their own OpenAI, Gemini, or Anthropic keys.
Secure & Temporary Storage
Keys encrypted at rest with pgcrypto and configurable TTL.
Automatic Cleanup
pg_cron automatically deletes expired keys. All benefits of BYOK, none of the liability.
Built for Enterprise Scale & Data Control
Not a simple SaaS tool—a production-grade stack for enterprise deployment. On-prem control with cloud flexibility.
Your Cloud, Your Data
Run the Gateway and Control Plane in your own K8s cluster. Prompts, keys, and responses never leave your network.
Flexible Hybrid Model
Use our managed Classifier in our cloud, or deploy the entire stack in your VPC. Your choice.
Kubernetes-Native
K8s-native, packaged with Helm for easy deployment to GKE, EKS, AKS, or self-hosted clusters.
Idempotent & Safe Deployments
Database migrations run automatically as K8s Jobs before services start. Safe, idempotent, clean rollbacks.
Get the Control You Need and the Scalability You Deserve.
Stop building brittle, insecure AI apps. Start building on a true enterprise-grade control plane.