cost-optimization
について
このスキルは、未使用リソースの特定、インフラの適正規模化、ベンダー契約の最適化を通じて、開発者がクラウドおよびSaaSコストを監査・削減することを支援します。予算見直し、契約更新時、または財務部門が支出増加を指摘した際に発動します。目的は、システムの信頼性や開発速度を損なうことなく、不要な経費を削減することです。
クイックインストール
Claude Code
推奨npx skills add rampstackco/claude-skills -a claude-code/plugin add https://github.com/rampstackco/claude-skillsgit clone https://github.com/rampstackco/claude-skills.git ~/.claude/skills/cost-optimizationこのコマンドをClaude Codeにコピー&ペーストしてスキルをインストールします
ドキュメント
Cost Optimization
Audit cloud, SaaS, and infrastructure spend. Cut what's not earning its keep. Rightsize what's oversized. Negotiate what's negotiable. Without breaking what works.
When to use
- Quarterly or annual cost review
- Finance flags rising spend
- Vendor contract renewal coming up
- Budget cut required
- New leadership wants the numbers
- Migrating between providers (cost is part of the case)
- Audit before scaling significantly (catch waste before it scales)
When NOT to use
- Active incident response (use
incident-response) - Performance issues that happen to involve infrastructure (use
performance-optimization) - Vendor evaluation for a new purchase (use
vendor-evaluation) - Personnel or org costs (out of scope for this skill)
Required inputs
- Current cost (monthly, ideally for the last 12 months)
- Cost broken down by service or vendor
- Inventory of cloud resources (instances, databases, storage, etc.)
- Inventory of SaaS subscriptions
- Owners per cost line (who decided to spend this, who uses it)
- Constraints (compliance, performance, contract terms)
The framework: 5 levers
Every cost optimization opportunity falls into one of these levers.
Lever 1: Eliminate
Stop paying for things that aren't used.
- Idle resources (instances, databases, environments running but unused)
- Subscriptions where no one logs in
- Duplicate tools (multiple tools doing the same job)
- Old projects still incurring cost
- Test environments that should have been torn down
- Forgotten domains, backups, snapshots, logs
This is usually the largest opportunity in the first audit. Often 10-30% of spend.
Lever 2: Rightsize
Pay for what you actually use, not what you provisioned for the worst case three years ago.
- Oversized instances (CPU and memory utilization low)
- Over-provisioned databases (storage and throughput far above usage)
- Over-purchased SaaS seats
- Premium plans where standard would suffice
- High-availability setups for non-critical systems
Rightsizing requires real usage data, not theoretical needs.
Lever 3: Restructure
Use cheaper structures for the same workload.
- Reserved or committed-use pricing (1-3 year commitments at 30-70% discount)
- Spot or preemptible instances for fault-tolerant work
- Cold storage for data accessed rarely
- Tiered storage (hot/warm/cold) by access pattern
- CDN caching to reduce origin load
- Compression and deduplication
- Serverless for spiky workloads
- Reserved instances for steady workloads
The right structure depends on the access pattern. Mismatch costs money.
Lever 4: Negotiate
Pay less for the same thing.
- Annual contracts at lower rates than monthly
- Volume discounts at higher tiers
- Multi-year commitments for predictable workloads
- Bundle deals (consolidating services with one vendor)
- Renewal negotiation (vendors expect you to ask)
- RFP / competitive bid (using alternatives as leverage)
Most enterprise vendors negotiate. Most SaaS vendors don't, except at higher tiers. Consumer-tier services usually don't.
Lever 5: Reframe
Change the question.
- Build vs buy: maybe in-house is cheaper at scale
- Buy vs build: maybe outsourcing is cheaper at small scale
- Different architecture (e.g., monolith vs microservices) has different cost profiles
- Different audience (do all customers need the same tier?)
- Different stack (open source vs commercial)
Reframe is the longest-lead lever. Worth thinking about even if not actionable now.
Workflow
Step 1: Pull the spend data
Get monthly costs by service, vendor, and (where possible) team or project.
For cloud (AWS, GCP, Azure): the billing console and cost-explorer tools. For SaaS: each vendor's billing portal, plus an SaaS-management tool if available. For everything else: bank statements and accounting export.
12 months minimum. Trends matter as much as absolute numbers.
Step 2: Categorize
Organize spend into categories:
- Hosting / compute
- Storage
- Database
- Networking / CDN
- Monitoring / observability
- CMS / hosting platforms
- Analytics / marketing
- Productivity / collaboration
- Development tools
- Security / compliance
- Other
The categories vary by business. The point is: similar costs grouped, easy to compare.
Step 3: Identify the biggest line items
80/20 rule. Usually 20% of vendors account for 80% of spend.
Focus the audit on the top 80%. The long tail can be cleaned up but rarely yields big savings per item.
Step 4: Apply the 5 levers
For each major line item, walk the levers:
| Lever | Question |
|---|---|
| Eliminate | Is it used? Could we stop using it? |
| Rightsize | Are we paying for capacity we don't use? |
| Restructure | Is there a cheaper pricing model or service tier? |
| Negotiate | When was the last renewal? Did we negotiate? |
| Reframe | Is this even the right approach? |
Document the opportunity, the effort, the risk, and the savings estimate.
Step 5: Prioritize
Plot opportunities on a 2x2:
- Y axis: savings
- X axis: effort
Quadrants:
- High savings, low effort: do first
- High savings, high effort: plan
- Low savings, low effort: do as time allows
- Low savings, high effort: skip
Also consider risk:
- Eliminate something used by no one: low risk
- Rightsize a database: medium risk (test in staging first)
- Replace a critical dependency: high risk (plan carefully)
Step 6: Execute the easy wins
For each easy-win opportunity:
- Document the change
- Get owner approval
- Make the change
- Monitor for unexpected impact
- Confirm cost reduction in next billing cycle
Easy wins typically include:
- Canceling unused subscriptions
- Tearing down idle resources
- Switching off dev environments outside business hours
- Moving cold data to cheaper storage tiers
Step 7: Plan the larger work
For higher-effort opportunities:
- Spec the change (use
pm-spec-writingfor the plan) - Test in staging
- Roll out incrementally
- Validate cost impact
Examples:
- Migrating to reserved instances
- Consolidating monitoring vendors
- Migrating from one CMS to another with cost benefit
Step 8: Set up ongoing visibility
Optimization isn't one-time. Costs creep back up.
- Monthly cost review (at least)
- Cost dashboard (current, trend, by category)
- Alerts on cost spikes (e.g., daily spend exceeds threshold)
- Tagging or labeling on cloud resources (cost by team or project)
- Quarterly deeper review
Step 9: Negotiate at renewal
For vendor contracts up for renewal:
- Start the conversation 60-90 days before renewal
- Have alternatives identified (even if you don't switch)
- Ask for a multi-year discount
- Ask about volume tiers
- Ask if usage rightsizing is possible
- Be willing to walk (most vendors find a way to keep you)
Pre-pandemic, many vendors auto-renewed at increases. Post-pandemic, many are hungry for retention. Ask.
Step 10: Document the policy
Going forward:
- New vendor evaluation requires cost justification
- Resource provisioning has approval thresholds
- Tagging and labeling are required for cloud resources
- Quarterly review is calendared
- Cost attribution is clear
Without policy, costs creep.
Common opportunities by category
Hosting and compute
- Reserved or committed-use pricing for predictable workloads (30-70% off)
- Spot or preemptible for fault-tolerant batch
- Auto-scaling for variable loads
- Right instance family (compute-optimized, memory-optimized, etc.)
- Dev/staging instances stopped outside business hours
Storage
- Lifecycle policies to move old data to cheaper tiers
- Delete old logs, backups, snapshots
- Compression for archival
- Object versioning costs (every version is a stored object)
Database
- Right size based on actual CPU/memory usage
- Reserved capacity for predictable workloads
- Read replicas for read-heavy workloads (cheaper than scaling primary)
- Drop unused indexes (indexes cost storage and write performance)
- Old data archived or deleted
Networking and CDN
- CDN reduces origin egress costs (often the biggest cost category)
- Compression on the wire
- Image and video optimization
- Region-aware routing
Monitoring and observability
- Sample logs (don't ingest 100% of high-volume sources)
- Retention policies (do you need 90 days or 30?)
- Consolidate tools where possible
- Free or open-source tooling for non-critical needs
SaaS
- Audit logins per seat (inactive users on $X/seat = $X waste)
- Renegotiate at renewal
- Move to annual billing for the discount
- Consolidate overlapping tools
Failure patterns
Cost-cutting that breaks something. Aggressive rightsizing without testing causes outages. The cost of an outage is usually larger than the savings.
Optimization that takes more time than it saves. A team spends a quarter saving $5K/year. Math doesn't work. Focus on opportunities where savings exceed effort.
Renewal autopilot. Annual renewals go through without review. Calendar them.
No tagging. Cloud spend grows; no one knows whose. Tag everything from day one.
Free tier overruns. "It's on the free tier." Then it's not, and bills surprise. Set alerts on free-tier services.
No environment differentiation. Production-grade staging "to match prod." Costs as much as prod. Often unnecessary.
Untouched legacy. "The old project still runs." Why? Often: nothing actually uses it. Audit and shut down.
Premium tiers for non-premium needs. Enterprise plan because someone wanted a feature that's been since added to lower tiers. Recheck.
Vendor lock-in justifying cost. "We can't switch." That's not a reason to overpay; it's a strategic problem to plan around.
Optimizing the small stuff while ignoring the big stuff. Saving $50/month on tools while $5K/month sits in oversized infrastructure. Top-down first.
Penny-wise, pound-foolish. Cutting a useful tool to save $20/month, then losing hours to manual work. Tools that pay for themselves shouldn't be cut.
No reinvestment. Every dollar saved goes to bottom line; nothing reinvested in upgrades or capacity. Saved costs and improved capability aren't either/or.
Output format
A cost optimization document includes:
- Current state: total spend, by category, trended
- Top line items: the biggest costs
- Opportunities: by lever (eliminate / rightsize / restructure / negotiate / reframe)
- Prioritized list: with savings, effort, risk
- Action plan: owners, dates
- Easy wins executed: what's already done, results
- Ongoing governance: dashboard, review cadence, tagging, approval thresholds
Reference files
references/cloud-audit-checklist.md: A practical walkthrough for auditing a cloud account (compute, storage, database, network, monitoring) for waste and rightsizing opportunities.
GitHub リポジトリ
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