API security
Know what you expose. Decide who can act. Put resource-level permissions at the center of your API design.
Explore API security API + AI security, connected
Every request.
Every agent.
A clearer picture.
Bring your API security, AI monitoring, and token controls into focus. Practical guidance for building smarter boundaries—not just adding another layer.
✓ Developer-first guidance✓ Real boundaries, not black boxes
Clarity by designFrom request to execution
GET /invoices/:idOwnership checked✓ Allowagent / export-recordsReview required◌ Approvalmodel / next-stepWorkflow budget◷ PauseAn architecture example—not connected traffic.
API securityAPI firewallAI API monitorAI API agentAI Token SentinelPrompt securityLeast privilegeClearer telemetry
Validate the requestAuthorize the actionFollow the workflowAccount for the tokensProtect the boundaryLearn. Test. Improve.
THE SENTINEL APPROACH
Different layers.
One thoughtful security plan.
Explore the boundaries that matter—from your public APIs to the agents and model calls behind them.
API firewall
Set clear request contracts, bound expensive work, and roll out traffic policies with intention.
Explore API firewallAI API monitor
Connect model calls, tool outcomes, and policy decisions into a workflow you can actually understand.
Explore AI API monitorAI API agent
Give tool-using agents scoped capabilities, explicit permissions, and accountable execution.
Explore AI API agentAI Token Sentinel
Attribute usage, reserve budgets, and make every model call part of a deliberate consumption plan.
Explore AI Token SentinelPrompt security
Keep system instructions, user requests, retrieved content, and tool results distinct in the application design.
Explore Prompt securityFROM QUESTIONS TO CONTROLS
Make the invisible, visible.
Start with the actual workflow. Decide what should happen. Keep the evidence that explains what did.
Know your boundaries.
Identify routes, actors, resources, and the systems allowed to change them. Name the owner of each decision.
Start with the checklist ↗Put policy into practice.
Define resource permissions, request contracts, and workflow budgets. Test what should be denied, too.
Explore a policy example ↗Close the feedback loop.
Connect decisions to outcomes. Review gaps, investigate unexpected behavior, and improve the next release.
Understand AI monitoring ↗AUTONOMY NEEDS BOUNDARIES
Let the model propose.
Let policy decide.
Agents can connect the dots. Your application still needs to decide which dots they are allowed to connect.
✓Scope access to the actual user, tenant, and task.
✓Keep consequential approvals specific and reviewable.
✓Track the difference between proposed and completed work.
Agent execution policyReference pattern
Identity & tenant contextVerify
Resource permissionsAuthorize
Workflow consumptionBudget
Consequential actionApprove
Decision & executionRecord
Prompt instructions are not a substitute for server-side permission checks.
THE SENTINEL JOURNAL
Less guesswork. Better decisions.
Practical, source-linked guides for the people building and protecting APIs.
API security
API security checklist: build a stronger first line of defense
A practical path from endpoint inventory to access controls, resource limits, and a release process your team can repeat.
AI & agents
AI agent least privilege: let the model propose, let policy decide
A permission model for tool-using agents, with scoped identities, specific approvals, and auditable execution.
Tokens & telemetry
AI token budgets: control consumption before the bill arrives
Design per-request, workflow, and tenant budgets with explicit estimates, reconciliation, and safe stopping behavior.
GOOD QUESTIONS, CLEAR ANSWERS
Start with the essentials.
Security is easier to discuss when the terms—and their limits—are clear.
What is API Sentinel?
APISentinel.com is a practical knowledge hub for API security, API firewall architecture, AI monitoring, agent permissions, and token control. Explore the field guides and local examples to plan your own implementation.
Can I connect my production API here?
No. This website provides guidance and interactive architecture examples, not a hosted firewall or monitoring backend. It does not request credentials or process production API traffic.
Where do API and AI security meet?
They meet where identity, data access, and tool execution cross boundaries. Model behavior adds new considerations, but applications still need explicit permissions, bounded resources, and useful operational evidence.
What should I read first?
Start with the API security checklist for an overall review, then choose the guide that matches your immediate concern: object access, request limits, agent permissions, token budgets, or incident response.