LLMFly AI

DEVELOPER TOOLS

Free LLM API Developer Tools & Calculators

Run pre-deployment checks directly in your browser without creating an account or uploading private prompts. Estimate multi-provider token spend, generate exact client configurations, and catch HTTP 400 schema errors before sending live traffic.

01

Choose a topic

01
Cost & Token Utility

LLM Token Counter & Cache Cost Calculator

Paste a system prompt or RAG payload to estimate subword tokens, simulate prompt-cache hit ratios, and compare 30-day costs across GPT, Claude, Gemini, and Grok.

02
Client Setup Utility

Claude Code, Codex & SDK Config Generator

Generate ready-to-copy settings.json, config.toml, Cursor overrides, OpenAI Python/TypeScript snippets, and curl smoke tests with exact catalog model IDs.

03
Schema Linter & Auto-Fixer

Structured Outputs JSON Schema Validator

Detect missing additionalProperties: false, incomplete required arrays, and unsupported keywords that trigger HTTP 400 errors across OpenAI, Claude, and Gemini.

Practical guidance

Why verify token economics and wire formats before deployment

Most production LLM surprises come from three preventable gaps: underestimating multi-turn or long-context input volume, pointing a CLI agent at the wrong wire endpoint, or shipping a JSON Schema that passes local TypeScript checks yet fails upstream strict-mode validation with HTTP 400.

Each utility on this page isolates one of those failure modes using the same Model Plaza snapshot and gateway protocol rules used across LLMFly AI.

  • Check whether your prompt crosses the 100K, 200K, or 272K long-context billing boundary before scaling concurrency.
  • Separate Anthropic-style Claude Code environment variables from OpenAI-compatible /v1/responses and /v1/chat/completions clients.
  • Normalize nested object schemas once instead of debugging opaque invalid_json_schema errors in production logs.

Browser-local execution and data privacy

System prompts, customer support transcripts, and internal tool schemas often contain proprietary business logic. None of the interactive tools in this directory transmit pasted text over the network—token estimation, config generation, and AST schema normalization run entirely in client-side JavaScript.

Frequently asked questions

Do these developer tools require an LLMFly AI account or API key?

No. Every calculator, config generator, and schema validator runs in your browser without registration or an API key.

Are pasted prompts or JSON Schemas uploaded to a server?

No. Calculations and schema checks execute locally in browser memory and are discarded when you close or reload the tab.

Where do the model prices in the token calculator come from?

Rates come from the bundled LLMFly AI Model Plaza snapshot, with platform multipliers and provider reference tiers evaluated independently.

Ready to run a live API call?

Create a scoped server-side key, copy a verified model ID, and confirm token counts in your usage log.

Get API Key