Site-wide A/B experiments

[smallbrownbike]

Changes

• Adds Vercel edge middleware to A/B test two full posthog.com builds at the same URL via PostHog feature flags
• Evaluates /flags on each request; rewrites test traffic to a separate deployment, passes control through to master
• Records experiment exposure client-side via getFeatureFlag() in posthog-init.js when SITE_EXPERIMENT_ENABLED=true at build time
• Moves /api product page to src/pages/product-api so Vercel does not treat it as a serverless API route
• Adds handbook docs at /handbook/engineering/posthog-com/site-experiments

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
posthog	Ready	Preview	Jul 15, 2026 9:45pm

[github-actions]

Deploy preview

Status	Details	Updated (UTC)
🟢 Ready	View preview	Jul 15, 2026 10:02PM

[github-actions]

Vale prose linter → found 14 errors, 61 warnings, 0 suggestions in your markdown

Full report → Copy the linter results into an LLM to batch-fix issues.

Linter being weird? Update the rules!

contents/handbook/engineering/posthog-com/developing-the-website.md — 14 errors, 53 warnings, 0 suggestions

Line	Severity	Message	Rule
11:12	warning	Use 'PostHog' instead of 'posthog'.	Vale.Terms
15:4	warning	'Option 1: Running with Codespaces' heading should be in sentence case, and product names should be capitalized.	PostHogBase.SentenceCase
15:27	warning	'Codespaces' is a possible misspelling.	PostHogBase.Spelling
17:5	warning	'Creating/running the Codespace' heading should be in sentence case, and product names should be capitalized.	PostHogBase.SentenceCase
17:26	warning	'Codespace' is a possible misspelling.	PostHogBase.Spelling
19:14	warning	Use 'PostHog' instead of 'posthog'.	Vale.Terms
19:65	warning	Use 'PostHog' instead of 'posthog'.	Vale.Terms
20:42	warning	'Codespaces' is a possible misspelling.	PostHogBase.Spelling
28:27	warning	'Codespaces' is a possible misspelling.	PostHogBase.Spelling
43:92	warning	'Cmd' is a possible misspelling.	PostHogBase.Spelling
51:1	error	'to' is repeated!	Vale.Repetition
78:53	warning	'Codespaces' is a possible misspelling.	PostHogBase.Spelling
78:71	warning	'codespace' is a possible misspelling.	PostHogBase.Spelling
82:27	warning	'codespace' is a possible misspelling.	PostHogBase.Spelling
82:120	warning	'Codespaces' is a possible misspelling.	PostHogBase.Spelling
84:4	warning	'Option 2: Editing posthog.com locally' heading should be in sentence case, and product names should be capitalized.	PostHogBase.SentenceCase
84:22	warning	Use 'PostHog' instead of 'posthog'.	Vale.Terms
91:60	warning	Use 'X' instead of 'x'.	Vale.Terms
92:54	warning	Use 'X' instead of 'x'.	Vale.Terms
103:5	warning	'Cloning the posthog.com repository' heading should be in sentence case, and product names should be capitalized.	PostHogBase.SentenceCase
103:17	warning	Use 'PostHog' instead of 'posthog'.	Vale.Terms
118:111	warning	Use 'PostHog' instead of 'posthog'.	Vale.Terms
128:34	warning	Use 'PostHog' instead of 'posthog'.	Vale.Terms
134:105	warning	Use 'PostHog' instead of 'posthog'.	Vale.Terms
136:76	warning	'Dialogs' is a possible misspelling.	PostHogBase.Spelling
144:5	warning	'Running posthog.com locally' heading should be in sentence case, and product names should be capitalized.	PostHogBase.SentenceCase
144:13	warning	Use 'PostHog' instead of 'posthog'.	Vale.Terms
159:47	warning	Use 'PostHog' instead of 'posthog'.	Vale.Terms
167:264	warning	Use 'PostHog' instead of 'posthog'.	Vale.Terms
193:113	error	Hi, Andy here... use an en dash ( – ) with spaces. On Mac, holding down the Option and hyphen key will give you an en dash.	PostHogBase.EnDash
193:216	warning	'Sourcemap' is a possible misspelling.	PostHogBase.Spelling
195:5	warning	'PR preview deployments (Cloudflare Pages)' heading should be in sentence case, and product names should be capitalized.	PostHogBase.SentenceCase
203:43	error	Hi, Andy here... use an en dash ( – ) with spaces. On Mac, holding down the Option and hyphen key will give you an en dash.	PostHogBase.EnDash
204:45	error	Hi, Andy here... use an en dash ( – ) with spaces. On Mac, holding down the Option and hyphen key will give you an en dash.	PostHogBase.EnDash
205:31	error	Hi, Andy here... use an en dash ( – ) with spaces. On Mac, holding down the Option and hyphen key will give you an en dash.	PostHogBase.EnDash
209:93	warning	'Ashby' is a possible misspelling.	PostHogBase.Spelling
213:19	warning	Capitalize 'Experiments' for PostHog's product. Use 'experiments' for the general industry concept.	PostHogBase.ProductNames
215:126	warning	Capitalize 'Experiments' for PostHog's product. Use 'experiments' for the general industry concept.	PostHogBase.ProductNames
225:38	warning	Use 'Markdown' instead of 'markdown'.	Vale.Terms
231:20	error	Hi, Andy here... use an en dash ( – ) with spaces. On Mac, holding down the Option and hyphen key will give you an en dash.	PostHogBase.EnDash
233:25	error	Hi, Andy here... use an en dash ( – ) with spaces. On Mac, holding down the Option and hyphen key will give you an en dash.	PostHogBase.EnDash
243:51	warning	'frontmatter' is a possible misspelling.	PostHogBase.Spelling
270:20	error	Hi, Andy here... use an en dash ( – ) with spaces. On Mac, holding down the Option and hyphen key will give you an en dash.	PostHogBase.EnDash
274:20	error	Hi, Andy here... use an en dash ( – ) with spaces. On Mac, holding down the Option and hyphen key will give you an en dash.	PostHogBase.EnDash
280:6	warning	'Frontmatter' is a possible misspelling.	PostHogBase.Spelling
282:28	warning	'frontmatter' is a possible misspelling.	PostHogBase.Spelling
282:101	warning	'frontmatter' is a possible misspelling.	PostHogBase.Spelling
310:33	warning	'src' is a possible misspelling.	PostHogBase.Spelling
311:26	warning	'Cloudinary' is a possible misspelling.	PostHogBase.Spelling
312:45	error	Hi, Andy here... use an en dash ( – ) with spaces. On Mac, holding down the Option and hyphen key will give you an en dash.	PostHogBase.EnDash
340:33	warning	'src' is a possible misspelling.	PostHogBase.Spelling
341:26	warning	'Cloudinary' is a possible misspelling.	PostHogBase.Spelling
348:7	warning	'Docs & Handbook' heading should be in sentence case, and product names should be capitalized.	PostHogBase.SentenceCase
367:63	warning	'frontmatter' is a possible misspelling.	PostHogBase.Spelling
416:26	warning	'Cloudinary' is a possible misspelling.	PostHogBase.Spelling
439:41	error	Hi, Andy here... use an en dash ( – ) with spaces. On Mac, holding down the Option and hyphen key will give you an en dash.	PostHogBase.EnDash
440:32	error	Hi, Andy here... use an en dash ( – ) with spaces. On Mac, holding down the Option and hyphen key will give you an en dash.	PostHogBase.EnDash
449:57	warning	'Cloudinary' is a possible misspelling.	PostHogBase.Spelling
453:25	warning	Use 'Markdown' instead of 'markdown'.	Vale.Terms
575:33	warning	Use 'GitHub' instead of 'github'.	Vale.Terms
577:60	warning	Use 'PostHog' instead of 'posthog'.	Vale.Terms
593:172	warning	'erroring' is a possible misspelling.	PostHogBase.Spelling
593:200	warning	'erroring' is a possible misspelling.	PostHogBase.Spelling
605:203	warning	Use 'PostHog' instead of 'posthog'.	Vale.Terms
619:31	error	Hi, Andy here... use an en dash ( – ) with spaces. On Mac, holding down the Option and hyphen key will give you an en dash.	PostHogBase.EnDash
620:36	error	Hi, Andy here... use an en dash ( – ) with spaces. On Mac, holding down the Option and hyphen key will give you an en dash.	PostHogBase.EnDash
624:30	warning	Use 'PostHog' instead of 'posthog'.	Vale.Terms

contents/handbook/engineering/posthog-com/site-experiments.mdx — 0 errors, 4 warnings, 0 suggestions

Line	Severity	Message	Rule
2:22	warning	Capitalize 'Experiments' for PostHog's product. Use 'experiments' for the general industry concept.	PostHogBase.ProductNames
7:51	warning	Use 'PostHog' instead of 'posthog'.	Vale.Terms
50:7	warning	'Googlebot' is a possible misspelling.	PostHogBase.Spelling
60:209	warning	'inlined' is a possible misspelling.	PostHogBase.Spelling

src/lib/README-site-experiments.md — 0 errors, 4 warnings, 0 suggestions

Line	Severity	Message	Rule
1:17	warning	Capitalize 'Experiments' for PostHog's product. Use 'experiments' for the general industry concept.	PostHogBase.ProductNames
3:54	warning	Use 'PostHog' instead of 'posthog'.	Vale.Terms
5:38	warning	Use 'PostHog' instead of 'posthog'.	Vale.Terms
5:55	warning	Capitalize 'Experiments' for PostHog's product. Use 'experiments' for the general industry concept.	PostHogBase.ProductNames

[github-actions]

Bundle report

Total JS (gzip)

6.31 MiB (+0.2 KiB / +0.0%)

Largest changed named chunks

Chunk	Gzip	Δ vs master
component---src-pages-product-api-index-tsx.js	2.0 KiB	new

Eager graph (modules shipped in each entrypoint's initial chunks)

Entrypoint	Eager size	Budget	Modules
✅ app	15.60 MiB (+2.1 KiB / +0.0%)	report-only	1945

Largest modules in the app closure

Module	Size
css ./node_modules/.pnpm/css-loader@5.2.7_webpack@5.101.3/node_modules/css-loader/dist/cjs.js??ruleSet[1].rules[8].oneOf[1].use[1]!./node_modules/.pnpm/postcss-loader@4.3.0_postcss@8.5.6_webpack@5.101.3/node_modules/postcss-loader/dist/cjs.js??ruleSet[1].rules[8].oneOf[1].use[2]!./src/styles/global.css	711.1 KiB
./src/components/Stickers/Stickers.tsx	696.4 KiB
./.cache/caches/gatsby-plugin-mdx/mdx-scopes-dir/31a094f140f119e73085d847ae81b99b.js + 2 modules	629.3 KiB
./node_modules/.pnpm/@radix-ui+react-icons@1.3.2_react@18.3.1/node_modules/@radix-ui/react-icons/dist/react-icons.esm.js	481.4 KiB
./node_modules/.pnpm/rehype-raw@7.0.0/node_modules/rehype-raw/lib/index.js + 29 modules	395.1 KiB
./node_modules/.pnpm/@posthog+icons@0.36.6_react-dom@18.3.1_react@18.3.1__react@18.3.1/node_modules/@posthog/icons/dist/posthog-icons.cjs.js	364.8 KiB
./src/hooks/useCustomers.tsx + 54 modules	355.1 KiB
./node_modules/.pnpm/@posthog+icons@0.36.6_react-dom@18.3.1_react@18.3.1__react@18.3.1/node_modules/@posthog/icons/dist/posthog-icons.es.js	354.8 KiB
./node_modules/.pnpm/react-markdown@8.0.7_@types+react@16.14.66_react@18.3.1/node_modules/react-markdown/lib/react-markdown.js + 88 modules	351.4 KiB
./node_modules/.pnpm/cloudinary-core@2.14.0_lodash@4.17.21/node_modules/cloudinary-core/cloudinary-core.js	281.9 KiB
./src/components/ProductComparisonTable/index.tsx + 120 modules	278.5 KiB
./node_modules/.pnpm/d3@7.9.0/node_modules/d3/src/index.js + 208 modules	247.4 KiB
./src/components/Pricing/PricingSlider/Slider.tsx + 87 modules	239.9 KiB
./gatsby-browser.tsx + 41 modules	239.8 KiB
./src/components/SearchUI/index.tsx + 73 modules	223.4 KiB

---

Eager-graph budgets are report-only until a baseline is established. Sizes are gzip of public/**/*.js; eager size is webpack module source bytes for the modules actually shipped in the entrypoint's initial chunks (post-tree-shake).