API hosting
$20/mo
Railway · Pro
API, workers and cron in one project with usage-based billing
railway.com ↗SaaS backend
The backend most SaaS products need: API, Postgres, sign-in, background jobs, cache, file storage and transactional email.
Good fit: B2B or B2C web apps from first customers to a few thousand paying accounts, built by a small team.
- Infrastructure
- $179/mo
- $164 at half the usage · $239 at double
- Payment fees (Stripe)
- 2.9% + 30¢ per transaction
- ≈ $234 at 200 payments · grows with your revenue, so it's not in the infrastructure total
How the parts connect
Hover or click a part to see what flows between them. Drag to move, use the buttons to zoom.
- API hosting$20/mo
Railway · Pro
- Background jobs$99/mo
Inngest · Pro
← enqueue from API hosting
- Database$19.43/mo
Neon · Launch
← queries from API hosting · read / write from Background jobs
- Authentication$20/mo
Clerk · Pro
← verify sessions from API hosting
- Cache & rate limits$6/mo
Upstash · Pay as You Go
← cache, rate limits from API hosting
- File storage$0
Cloudflare R2
← signed uploads from API hosting
- Transactional email$15/mo
Postmark · Basic
← send from Background jobs
- Payments2.9% + 30¢
Stripe · US cards
← checkout, webhooks from API hosting
Monthly cost
EstimateExpected cost at the usage below, and the range from half to double that usage. Worked out from each vendor's current prices and free tiers; your real bill depends on your traffic.
| Part | Pick | Expected / mo | Range |
|---|---|---|---|
| API hosting | Railway · Pro | $20/mo | fixed |
| Database | Neon · Launch | $19.43/mo | $8.04–$20.48 |
| Authentication | Clerk · Pro | $20/mo | fixed |
| Background jobs | Inngest · Pro | $99/mo | fixed |
| Cache & rate limits | Upstash · Pay as You Go | $6/mo | $1.50–$24 |
| File storage | Cloudflare R2 | $0 | $0–$0.45 |
| Transactional email | Postmark · Basic | $15/mo | $15–$54.60 |
| Infrastructure total | $179/mo | $164–$239 | |
Payment fees (Stripe · US cards): 2.9% + 30¢ per transaction
≈ $234 at 200 payments a month ($117–$468). Not in the infrastructure total: fees grow with your revenue, they aren't a cost of running the stack.
Show the arithmetic behind every number
API hosting · Railway · Pro
- vcpu = app_vcpu = 0.5
- ram_gb = app_ram_gb = 0.5
- Pro list price $20.00/month
- vCPU: 0.5 × 2,592,000 seconds × $0.00000772 = $10.01
- RAM GB: 0.5 × 2,592,000 seconds × $0.00000386 = $5.00
- usage $15.01 − included credit $20.00 = $0.00
Database · Neon · Launch
- db_gb = monthly_active_users / 1000 * data_gb_per_1k_users = 2,000 / 1000 × 0.5 = 1
- cu_hours = db_cu * db_active_hours = 0.25 × 720 = 180
- compute CU-hours: 180 × $0.106 = $19.08
- storage GB-month: 1 × $0.35 = $0.35
- note: Launch has no base fee; the $15 on the page is a typical bill
Authentication · Clerk · Pro
- mau = monthly_active_users = 2,000
- Pro list price $20.00/month
- monthly retained users: 2,000 − 50,000 free = 0 × $0.02 = $0.00
Background jobs · Inngest · Pro
- executions = monthly_active_users * jobs_per_user_per_month * (steps_per_job + 1) = 2,000 × 20 × (2 + 1) = 120,000
- job_runs = monthly_active_users * jobs_per_user_per_month = 2,000 × 20 = 40,000
- job_compute_seconds = monthly_active_users * jobs_per_user_per_month * job_seconds = 2,000 × 20 × 2 = 80,000
- Pro list price $99.00/month
- executions: 120,000 − 1,000,000 free = 0 ÷ 1,000,000 × $50.00 = $0.00
Cache & rate limits · Upstash · Pay as You Go
- commands = monthly_active_users * requests_per_user_per_month * cache_commands_per_request = 2,000 × 1,500 × 1 = 3,000,000
- Pay as You Go: metered plan, no base fee
- commands: 3,000,000 ÷ 100,000 × $0.20 (catalog: Pay as You Go) = $6.00
File storage · Cloudflare R2
- storage_gb = monthly_active_users / 1000 * storage_gb_per_1k_users = 2,000 / 1000 × 5 = 10
- write_ops = monthly_active_users * write_ops_per_user = 2,000 × 10 = 20,000
- read_ops = monthly_active_users * read_ops_per_user = 2,000 × 50 = 100,000
- storage GB-month: 10 − 10 free = 0 × $0.015 (catalog: Storage) = $0.00
- Class A (write) ops: 20,000 − 1,000,000 free = 0 ÷ 1,000,000 → 0 (rounded up) × $4.50 (catalog: Class A Operations) = $0.00
- Class B (read) ops: 100,000 − 10,000,000 free = 0 ÷ 1,000,000 → 0 (rounded up) × $0.36 (catalog: Class B Operations) = $0.00
Transactional email · Postmark · Basic
- emails = monthly_active_users * emails_per_user_per_month = 2,000 × 4 = 8,000
- Basic list price $15.00/month
- emails: 8,000 − 10,000 free = 0 ÷ 1,000 × $1.80 = $0.00
Payments · Stripe · US cards
- transactions = paying_customers = 200
- volume_usd = paying_customers * avg_transaction_usd = 200 × 30 = 6,000
- US cards: 2.9% + $0.30 per transaction (catalog)
- percentage: $6,000.00 volume × 2.9% = $174.00
- fixed: 200 transactions × $0.30 = $60.00
- payment fees grow with revenue, so they are shown apart from the infrastructure total
The tools, and why
Database
$19.43/mo
Neon · Launch
Serverless Postgres with a database branch per preview deploy
neon.com ↗Authentication
$20/mo
Clerk · Pro
Prebuilt sign-in UI plus organizations and roles for B2B
clerk.com ↗Background jobs
$99/mo
Inngest · Pro
Durable functions with retries, schedules and fan-out in your codebase
inngest.com ↗Cache & rate limits
$6/mo
Upstash · Pay as You Go
Serverless Redis billed per command; ready-made rate limiting
upstash.com ↗File storage
$0
Cloudflare R2
S3-compatible with no egress fees for downloads
cloudflare.com ↗Transactional email
$15/mo
Postmark · Basic
Best-in-class deliverability for password resets and receipts
postmarkapp.com ↗Payments
2.9% + 30¢ per transaction
Stripe · US cards
Subscriptions, invoices and hosted checkout with the lowest card fee here
stripe.com ↗All costs are estimates. Prices are read from each vendor's pricing page and checked every 12 hours (last: Oct 30, 2026); your bill depends on your traffic.
The usage these costs assume
"Half" and "double" in the ranges scale these numbers.
- Monthly active usersAn early-stage product with steady usage
- 2,000 users
- API requests per userAbout 50 requests per active day
- 1,500 requests/user/month
- Background jobs per userNotifications, webhooks and nightly tasks
- 20 jobs/user/month
- Emails per userSign-in links, notifications and a receipt
- 4 emails/user/month
- Database size per 1,000 usersTypical relational data without large blobs
- 0.5 GB
- Files per 1,000 usersAvatars, uploads and exports
- 5 GB
- Paying customersAbout 10% of active users pay
- 200 customers
- Average chargeA typical SaaS subscription price
- 30 USD/month
Engineering assumptions (9)
- API vCPUOne small API instance
- 0.5 vCPU
- API RAMOne small API instance
- 0.5 GB
- Database compute sizeThe smallest Neon compute
- 0.25 CU
- Database active hoursAn API with steady traffic keeps it awake
- 720 hours/month
- Steps per jobLoad data, then do the work
- 2 steps
- Compute per jobShort tasks like sending a webhook
- 2 seconds
- Redis commands per requestOne rate-limit check per API call
- 1 commands
- File writes per userUploads and generated exports
- 10 writes/user/month
- File reads per userAvatars and downloads
- 50 reads/user/month
How to build it
- 1
API and database
Set up the API project, connect Postgres, add migrations and a seed; deploy previews with their own database branch.
Uses: API hosting, Database
- 2
Sign-in and organizations
Add sign-up/sign-in, an organizations model and roles; check the session on every API route.
Uses: Authentication, API hosting
- 3
Email
Send verification, password reset and notification emails from templates; set up SPF, DKIM and DMARC.
Uses: Transactional email
- 4
Background jobs
Move slow work (emails, webhooks, imports) into retried jobs; add a nightly cleanup schedule.
Uses: Background jobs
- 5
Uploads
Let clients upload straight to object storage with signed URLs; record files in the database.
Uses: File storage, Database
- 6
Payments
Create products and prices, send customers to hosted checkout, and process webhooks in a job so subscriptions stay in sync.
Uses: Payments, Background jobs
- 7
Protect and speed up
Rate-limit by user and IP, cache the hottest reads, and add indexes for the slowest queries.
Uses: Cache & rate limits, Database
Not covered by this estimate
- Error monitoring (Sentry) and uptime checks: not in the catalog yet
Get this built for you
We'll adapt this blueprint to your product, set it up on your accounts and hand it over working, with the monthly bill you saw here.