toolooo · ToolboxTurn invisible problems
into visible ones.
Small browser tools that help you check, simulate, decide, plan and create. Useful, fast, beautiful — no signup, no backend, no bullshit.
Choose a question. Then make the moving parts visible.
Useful outputs to start with
Review a contract, explore service pressure, or make a drawing template. Everything runs in your browser.
API Payload Doctor
Paste an API request or response and get a structured diagnosis of what could go wrong with it.
Retry Storm Simulator
Compare retry policies and see how attempts, backoff, jitter, and budgets change recovery pressure.
Rate Limit Playground
Design and compare a rate-limit policy under steady traffic, bursts, overload, and client retries.
Start with the problem you’re solving
API contracts & integration
Inspect payloads, date contracts and consumer compatibility before a release.
Failures & recovery
Explore retries, queues and service behavior under explicit failure assumptions.
Design & delivery
Check content, accessibility and output constraints before handing work off.
Every tool answers one of these questions
Click a family to filter the tools below.
How deep does the tool go?
Levels describe experience maturity. Every current production tool targets LV2.
Input → Calculate → Result
Explore → See → Understand → Act
Connected workflows and deeper Toolooo experiences
Showing 70 of 70
API Error Contract Builder
Create consistent API errors with RFC 9457 JSON, safe messages and client recovery guidance.
Passkey Migration Planner
Plan a staged passkey rollout with recovery, fallback, shared-device and password-removal gates.
Workflow vs Agent vs Multi-Agent Decision Lab
Choose the simplest useful architecture: code, workflow, one agent, tools or independent specialists.
Cache Stampede Simulator
Compare hot-key expiry, duplicate origin work and cache protection strategies on a seeded virtual clock.
OpenTelemetry Trace Doctor
Check trace structure, timing, service identity and sensitive-data signals in static OTLP JSON.
MCP Tool Contract Builder
Create bounded MCP input/output schemas with separate approval, scope, retry and failure guidance.
AI Agent Permission Planner
Plan least-privilege agent capabilities, scope restrictions, human approvals and denied actions before connecting tools.
Real-Time Transport Decision Lab
Compare Polling, Long Polling, SSE, WebSocket and WebTransport against your communication and infrastructure needs.
AI Agent Cost & Loop Simulator
Compare agent token, retry, branch and model-cost growth against explicit guardrails using your own prices.
MCP Security Doctor
Review MCP tool and server JSON for risky capabilities, broad permissions, approval gaps and sensitive data signals.
Cloud Cost Guardrail Builder
Build owner-led spending guardrails with your budget thresholds, environment constraints and cost-category review rules.
UX Research Study Planner
Turn a product decision into a neutral study plan with suitable methods, recruitment, evidence and decision criteria.
LLM Output Assurance Decision Lab
Choose validation, review and failure-handling layers from an AI feature’s explicit risks and constraints.
SLO Incident Burn Simulator
Model request-based error-budget consumption through incident severity, detection, mitigation, recovery and traffic spikes.
Data Contract Drift Doctor
Compare JSON release samples for consumer-breaking changes, date/value-set drift and possible path movement.
UI Edge-State Matrix Builder
Draft editable UI state coverage with triggers, recovery behavior, QA checks and local JSON/CSV export.
Accessibility Remediation Planner
Turn observed accessibility barriers into phased fixes with dependencies, owners and verification actions.
Web Rendering Strategy Decision Lab
Rank rendering patterns against freshness, personalization, hosting and discovery requirements.
Network Failure UX Simulator
Compare seeded retry strategies, waiting, failures and recovery from the frontend user’s perspective.
Frontend Data Exposure Doctor
Review browser-visible data placement, masked exposure findings and context-aware safer directions.
LLM Eval Case Builder
Design and edit local evaluation case templates with explicit expectations, review notes and JSON export.
Web Performance Budget Planner
Derive project-specific resource budgets and compare optional measurements against transparent release gates.
Client State & Storage Decision Lab
Choose browser state and storage mechanisms with transparent fit scores, capability constraints and privacy cautions.
Browser Event Loop Simulator
Step through the call stack, microtasks, timers and rendering opportunities using safely parsed examples.
Browser Security Policy Doctor
Review CSP, HSTS and browser security headers together, with contextual findings and compatibility cautions.
API Chaos Payload Builder
Generate bounded JSON edge-case packs with typed mutations, nested paths and local copy/export.
Zero-Downtime Schema Change Planner
Plan compatible schema rollouts with phased deployment, data verification and honest rollback checkpoints.
Async Messaging Decision Lab
Compare Queue, Pub/Sub and Event Stream against delivery, replay, ordering and operational requirements.
Replica Lag Simulator
Trace stale replica reads and compare primary routing, post-write windows, sticky reads and lower lag.
Date & Time Contract Doctor
Find ambiguous timestamps, epoch-unit risks and unsafe lifecycle ordering in JSON, with safe UTC conversions.
API Payload Doctor
Paste an API request or response and get a structured diagnosis of what could go wrong with it.
JWT Time Machine
Decode a JWT and see its issued/valid/expiry claims plotted on an actual timeline.
CORS Doctor
Diagnose exactly which CORS rule is blocking a request, and why.
Print Ready Doctor
Check a photo or document against real print sizes and see exactly how sharp it will look at each one.
Schema Drift Doctor
Compare JSON or CSV samples and see where a data contract may have changed.
Environment Drift Detector
Compare environment configuration structures while keeping values masked by default.
Responsive Content Fit Lab
Resize your content and see where headings, copy, and actions start to struggle.
Webhook Delivery Simulator
See how failures, retries, and duplicate events affect webhook delivery and processing.
Capacity Cliff Simulator
Find when growing demand crosses your safe threshold and available capacity.
Retry Storm Simulator
Compare retry policies and see how attempts, backoff, jitter, and budgets change recovery pressure.
Cache Value Simulator
Simulate cache hit rate and staleness as you change TTL, eviction policy, and traffic pattern.
Rate Limit Playground
Design and compare a rate-limit policy under steady traffic, bursts, overload, and client retries.
Queue Capacity Planner
See when queues absorb bursts, build backlog, drain, or expose downstream capacity pressure.
SLA Chain Visualizer
Model required-path reliability, error-budget fit, and the assumptions behind a service objective.
Fan-Out Latency Simulator
Model fan-out tail latency, critical paths, optional work, and deadline headroom.
Circuit Breaker Playground
See when a circuit breaker stops calls to a failing dependency and how it tests recovery.
N+1 Query Visualizer
See how related-data loading multiplies database queries, round trips, and potential downstream pressure.
Connection Pool Simulator
See when callers wait for a pooled connection and how pool size, hold time, scale-out, and database budget interact.
HTTP Cache Lab
Configure Cache-Control, ETag, and Last-Modified headers and simulate how browsers and CDNs actually cache the response.
Scope Creep Visualizer
Add "small" extra asks to a freelance project one by one and watch your effective hourly rate shrink.
AI Project Pricing Lab
Compare AI-assisted effort with the risk, review, and support you still own.
Database Decision Lab
Weigh database options against your own priorities and see a transparent, scored recommendation.
Build vs Buy
Weigh building a feature in-house against buying a third-party service, scored against your own priorities.
Tech Stack Battle
Compare candidate tech stacks head-to-head, scored against your project's actual priorities.
Distributed Systems Tax
See the real cost of splitting a system into another network hop before you decide to do it.
Monolith vs Microservices Lab
Weigh monolith vs microservices for your actual team size and deployment cadence — not dogma.
REST vs GraphQL Decision Lab
Compare REST, GraphQL, and gRPC against your API's actual shape with a transparent, weighted score.
Multi-Format Campaign Planner
Group campaign destinations into reusable master compositions and see the crop tradeoffs.
API Pagination Planner
Compare pagination behavior and explore the tradeoff between page size and request count.
Sticky Note Frame Planner
Plan how sticky notes tile inside a frame or board — to scale, before you commit to a layout.
Timeout Chain Planner
Plan one end-to-end deadline across serial calls, retries, and remaining downstream budget.
Frame Fit Finder
See your artwork placed inside candidate frame sizes before you buy one.
Paper Nesting Planner
Plan how multiple pieces nest onto a sheet of paper or print stock with minimal wasted area.
Project Quote Risk Planner
See which line items in a client quote carry the most risk of scope or time overrun before you send it.
Roadmap Collision Detector
Lay multiple project timelines side by side and catch where they collide before it becomes a fire drill.
Crop Guardian
Crop one image to multiple target aspect ratios at once and export every crop, right in your browser.
Drawing Grid Maker
Generate and download a proportion grid overlay for any canvas size — for tracing, scaling, or practice.
Bleed & Safe Area Builder
Generate a downloadable bleed and safe-area guide for any print size.
Value Study Maker
Turn a reference photo into a simplified tonal value study to practice shading and composition from.
Perspective Grid Maker
Generate and download a customizable 1, 2, or 3-point perspective grid for drawing practice.
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