AI & LLM Tools

Brevio AI tools help developers build and test LLM applications. Every tool runs in your browser — no API key, no rate limit, no data sent to a server.

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Context Packer

Pack prioritized prompt blocks into a context-window budget while reserving output tokens.

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Context Window Visualizer

See how your prompt fills different LLM context windows. Compare Claude, GPT-4o, Gemini across 9 models.

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Few-Shot Prompt Builder

Build few-shot example collections for LLM prompts. Format for OpenAI, Claude, or plain text.

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Fine-Tune Cost Calculator

Estimate fine-tuning training tokens, training cost, and monthly inference cost from editable provider rates.

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HTTP Headers Decoder

Paste HTTP response headers to decode and understand each one. Covers security, caching, CORS and content headers.

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JSONL Formatter & Validator

Validate JSONL files line by line and convert between JSONL and JSON array. Free, in-browser.

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JWT Generator

Generate signed JWT tokens with HS256, HS384, or HS512. Add custom claims, set expiry, copy the token. Free, in-browser.

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LLM Benchmark Comparison

Compare Claude, GPT-4o, Gemini, Llama and more on MMLU, HumanEval, MATH, GPQA and pricing. Sortable table.

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LLM Cost Calculator

Calculate and compare LLM API costs for Claude, GPT-4o, Gemini, Llama and more. Enter token counts to see exact pricing.

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LLM Error Decoder

Decode LLM API errors from OpenAI, Anthropic, Gemini, and Groq. Get causes and fixes instantly.

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LLM Eval Scorecard

Score LLM outputs manually across accuracy, completeness, instruction following, safety, and clarity.

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LLM Memory Calculator

Calculate how much VRAM you need to run any LLM. Covers fp32, fp16, int8, int4 quantization and KV cache.

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LLM Response Comparator

Compare two LLM outputs by tokens, words, shared terms, and lexical cosine similarity. No API key.

Number to Words

Convert any number to English words instantly. Free, runs in your browser.

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Prompt Compressor

Trim whitespace, comments, and filler phrases from prompts to reduce approximate token count before sending to an LLM.

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Prompt Formatter

Convert system and user messages into OpenAI, Claude, Gemini, or Llama API format. Copy-paste ready JSON.

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Prompt Injection Scanner

Scan user inputs for common prompt injection patterns before sending to your LLM. Free, in-browser.

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RAG Chunk Previewer

Preview how your documents will be chunked for RAG (Retrieval-Augmented Generation). Adjust chunk size and overlap.

Readability Score

Check your text's Flesch Reading Ease and Flesch-Kincaid grade level instantly. Free, in-browser.

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String Escape Tool

Escape and unescape strings for JSON, HTML, SQL, Regex, and URL encoding. Free, runs in your browser.

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System Prompt Scorer

Score your LLM system prompt on 7 dimensions: role, task clarity, constraints, format, tone, context, and examples.

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Text Similarity Checker

Compare two texts for lexical similarity using cosine similarity. Fast, in-browser, no API key.

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Token Counter

Count tokens, words, and characters in any text. See how your text fits in Claude, GPT-4o, or Gemini context windows.

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Token Probability Visualizer

Convert candidate token logits into softmax probabilities and see how temperature changes model sampling.

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Tokenizer Visualizer

Visualize how your text is split into tokens for LLMs. See approximate token boundaries with color-coded highlights.

Frequently Asked Questions

Do I need an API key to use these tools?: No. All AI tools run locally in your browser. No API calls are made to OpenAI, Anthropic, or any other provider.
Is my prompt text sent anywhere?: No. Your prompts, system messages, and LLM outputs are processed entirely in browser JavaScript and never transmitted.
Are the pricing figures accurate?: LLM pricing is updated when providers change their rates. Always check the official provider pricing page before making billing decisions.

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