[Bccorb]

Closes #110

Draft for maintainer sign-off. Every price below was read on 2026-10-20 and should be re-checked on the day this is published; they all live in src/components/cost-calculator/pricing.ts with a source URL and checked date next to each.

What this adds

• src/content/docs/compare/cost.mdx: the Identity Cost Calculator page (list prices only, how each number is read, what the Seamless Auth number includes and leaves out, Sources).
• src/components/cost-calculator/CostCalculator.astro: an Astro island with an inline client script. Inputs: MAU, B2C or B2B, enterprise connections, MFA. No new dependencies, no external scripts, no runtime fetches.
• src/components/cost-calculator/pricing.ts: all prices and dates, plus the pure calculate() function.
• Links from compare/auth0.mdx (pricing Aside and the per-user bullet) and compare/keycloak.mdx (after Footprint). The Cognito and Firebase pages in docs: compare Seamless Auth with Cognito and Firebase Auth #128 are untouched.

Without JavaScript the form stays hidden and the page shows static tables of every published Auth0 price by MAU step, the Okta starting price, and the Seamless Auth hosting cost.

Rules the calculator follows

• A MAU count rounds up to the next step Auth0's slider shows (500, 1,000, 2,500, 5,000, 7,500, 10,000, 20,000, 30,000+). No interpolation.
• A step the page shows as "Get in touch", anything above 30,000 MAU, Auth0 Enterprise, and the Okta suites show "Contact sales" with a link to the vendor.
• Add-ons the page prices as "starting at" make the result "From $X".
• If a plan does not list the enterprise connections or MFA you pick, the result says so ("Not on this plan") instead of guessing.

Prices used

Item	Price	Source	Checked
Auth0 Free	$0, up to 25,000 MAU	https://auth0.com/pricing	2026-10-20
Auth0 B2C Essentials, MAU up to 500 / 1,000 / 2,500 / 5,000 / 7,500 / 10,000 / 20,000 / 30,000	$35 / $70 / $175 / $350 / $525 / $700 / $1,400 / $2,100 per month	https://auth0.com/pricing	2026-10-20
Auth0 B2C Professional, same steps	$240 / $240 / $545 / $1,000 / $1,200 / $1,600 / $3,200 / Get in touch	https://auth0.com/pricing	2026-10-20
Auth0 B2B Essentials, same steps	$150 / $300 / $700 / $1,300 / $1,725 / $2,100 / $3,800 / Get in touch	https://auth0.com/pricing	2026-10-20
Auth0 B2B Professional, same steps	$800 / $800 / $1,200 / $1,500 / $1,800 / $2,400 / Get in touch / Get in touch	https://auth0.com/pricing	2026-10-20
Auth0 Enterprise	Contact sales	https://auth0.com/pricing	2026-10-20
Auth0 enterprise connections included	Free 1, B2B Essentials 3, B2B Professional 5, B2C paid plans none	https://auth0.com/pricing	2026-10-20
Auth0 extra enterprise connection (B2B)	Starting at $100 monthly per active connection	https://auth0.com/pricing (tooltip)	2026-10-20
Auth0 Enterprise MFA add-on (B2B Essentials)	Starting at $100 monthly, SMS charged separately by carriers	https://auth0.com/pricing (tooltip)	2026-10-20
Okta Customer Identity Enterprise base platform	Starts at $3,000 per month, billed annually; add-ons priced on usage	https://www.okta.com/pricing/ (Customer Identity tab)	2026-10-20
Okta Customer Identity B2C Suite, B2B Suite	Inquire for pricing	https://www.okta.com/pricing/	2026-10-20
DigitalOcean Basic Droplet, Regular, 2 GiB, 1 vCPU, 50 GiB SSD	$12.00 per month	https://www.digitalocean.com/pricing/droplets	2026-10-20
DigitalOcean Managed PostgreSQL Standard, Basic node, 1 GiB, 1 vCPU, single node, 10 GiB	$15.15 per month	https://www.digitalocean.com/pricing/managed-databases	2026-10-20
DigitalOcean extra Standard Edition storage	$0.215 per GiB per month	https://docs.digitalocean.com/products/databases/postgresql/details/pricing/	2026-10-20
Seamless Auth self-hosted total	$27.15 per month, flat with MAU	sum of the two DigitalOcean rows	2026-10-20

Auth0 prices are monthly billing, read from the rendered pricing page at each slider step.

Things a reviewer should check

• Auth0 add-on wording. compare/auth0.mdx said extra B2B enterprise connections cost "$100 per month each, up to 30 in total". Today the pricing page says "Starting at $100 monthly per active connection" and I could not find the 30-connection cap anywhere on it, so this PR changes that sentence to the starting price and drops the cap.
• Okta has its own Customer Identity prices. okta.com/pricing has a Customer Identity tab, separate from the Auth0 pricing it links to, with the prices above. The calculator shows those prices. The Okta Customer Identity section of compare/auth0.mdx still says Okta sells Auth0 under that name; a maintainer may want to reword it.
• DigitalOcean rounding. The PostgreSQL details page says single node clusters start at $15.00 per month, while the Managed Databases pricing page lists $15.15 for the plan. The calculator uses $15.15 and the page explains the difference.
• No capacity claim. Seamless Auth has no published benchmark. The page calls the host size a starting point, not a measured capacity, and points to the idle memory measurement on the Keycloak page.
• Managed Seamless Auth pricing is not quoted; the page links to the portal.

Checks

• npm run lint: pass
• npm run typecheck: 0 errors, 0 warnings, 0 hints
• npm run build: 56 pages built, including /compare/cost/ (the existing env highlighting and i18n warnings are not from this change)
• npm run check:matrix: fails with 13 drifted packages, same as on main, unrelated to this change
• calculate() unit tested with node --test (6 cases: published starting prices, rounding up to the next step, contact sales above the published range, connection allowance and add-on, MFA by plan, Okta rows)
• Built site exercised in headless Chromium: the form renders and updates on input with no console errors; no horizontal scroll at 375px; with JavaScript disabled the form is hidden and both static price tables render