# API Media Types Vendor Content Types

> Choose and document HTTP media types including vendor trees (vnd), structured suffixes (+json), and MIME versioning. Use when minting custom types or reviewing Content-Type versioning schemes.

- Skill: `deangrant/api-media-types-vendor-content-types` (Agent Skill, multi-file: 4 files)
- Install (CLI): `npx skillmds@latest add deangrant/api-media-types-vendor-content-types`
- Raw SKILL.md: https://api.skillmd.com/api/skills/deangrant/api-media-types-vendor-content-types/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Integrations & APIs
- Author: deangrant (https://skillmd.com/u/deangrant)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/deangrant/api-media-types-vendor-content-types

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# Media Types and Vendor Content Types

Use this skill when selecting **media type identifiers** beyond plain JSON.

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## 1. Structure (RFC 6838)

`type/subtype; parameters` — case-insensitive names. Trees: standards, vendor
`vnd.`, personal `prs.`, unregistered `x.` (discouraged).

Structured suffix: `+json` / `+xml` so generic parsers still work.

Example: `application/vnd.api+json; version=2`

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## 2. Guidance

- Prefer standard types; mint `vnd.*` sparingly when semantics truly differ.
- Prefer OpenAPI/JSON Schema for structure over media-type explosion.
- Versioning: subtype version **or** `; version=` — pick one convention.
- JSON:API allows only `ext` and `profile` params — others → **415**.
- Always set Content-Type; `X-Content-Type-Options: nosniff`; `Vary: Accept`
  when format varies.

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## 3. Quick checklist

- [ ] Document request/response types.
- [ ] Accurate Content-Type; nosniff.
- [ ] 406/415 behavior defined.
- [ ] Consistent MIME versioning scheme if used.
- [ ] OpenAPI lists allowed types.

See [reference.md](reference.md) and [examples.md](examples.md).