AI model evaluation workspace

Evaluate AI models before production.

Compare models from OpenAI, Anthropic, and Google AI; test prompts, analyze costs and token usage, and understand context consumption before you choose the right model for your application.

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Improve Fetch Error Handling

Eidostack

Review this TypeScript function and suggest the most important improvement:

async function fetchUser(id: string) {
  const response = await fetch(`/api/users/${id}`);
  return response.json();
}

Check response.ok before parsing JSON; otherwise 4xx/5xx responses may be treated as valid data.
Encode the ID to prevent malformed URL paths.

tsCopy

async function fetchUser(id: string) {
const response = await fetch(`/api/users/$${encodeURIComponent(id)}`);
if (!response.ok) throw new Error(`Failed to fetch user: $${response.status}`);
return response.json();
}

7/17/2026 · GPT-5.6 Terra · 181 tokens · $0.0016

Most important improvement: error handling. fetch doesn't throw on HTTP errors (404, 500), so failures pass silently.

tsCopy

async function fetchUser(id: string): Promise<User> {
const response = await fetch(`/api/users/$${id}`);
if (!response.ok) {
throw new Error(`Failed to fetch user $${id}: $${response.statusText}`);
}
return response.json() as Promise<User>;
}

Check response.ok
Add return type for type safety

7/17/2026 · Claude Opus 4.8 · 311 tokens · $0.0051

Send to both models simultaneously… (Shift+Enter for new line)

GPT-5.6 TerraSys Prompt

BClaude Opus 4.8Sys Prompt

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The EidoStack desktop workspace for chats, model comparison, prompts, and usage.

A focused loop

From prompt to confident choice.

EidoStack keeps the evaluation loop visible: set up access, run a controlled experiment, and compare the evidence before production.

Bring your own keys

Connect supported providers with your own credentials. Your keys stay in a client-side encrypted vault.

Run the same experiment

Select a model, system prompt, and context strategy. Turn on comparison mode when you want two responses side by side.

Choose with evidence

Review response behavior alongside token usage, estimated cost, and context-window consumption.

Everything you need to choose with confidence.

A structured evaluation workflow for model behavior, cost, context, and prompts.

Compare model responses

Run one prompt against two selected models and compare responses side by side while you evaluate quality and behavior.

Work across providers

Connect OpenAI, Anthropic, or Google AI with your own API keys and keep provider access in one workspace.

Analyze tokens and cost

Track input and output tokens plus estimated provider cost per chat, model, and selected time range.

See context usage

Inspect estimated tokens against the selected model context window and choose full, windowed, or smart context.

Test system prompts

Configure system prompts for a chat, then observe how your instructions affect each model response.

Keep experiments organized

Create, automatically name, organize, and revisit chats as you work through model evaluations.

Bring your own API keys

Your provider access stays in your control.

EidoStack uses a client-side encrypted vault so you can evaluate models with your own provider accounts and understand exactly where requests and costs come from.

Set up your vault

Client-side encrypted vault

Protected by your master password

Provider keys are encrypted in your browser with a master password.
Encrypted key records are stored in browser storage; plaintext keys are held in memory only while the vault is unlocked.
Provider requests are made from your browser using your own credentials, keeping keys out of the EidoStack application server.
Encrypted vault backup and restore are supported when you need to move or recover your local setup.

Pricing for your evaluation workflow.

Bring your own provider keys. Pro access is currently available by request while checkout is being prepared.

Free

$0/month

Evaluate AI models with your own API key, inspect token and cost usage, understand context usage, and experience the core EidoStack workflow within these limits.

Maximum configured API providers: 1
Maximum chats: 5
Maximum messages per chat: 50
Model comparison mode: Not available
Inspect token usage and costs
Understand context usage

Start Evaluating

Make model selection an evidence-based decision.

Bring your own API keys, run your prompts, and see the trade-offs before a model becomes part of your production stack.

Start evaluating