[demo of #2573] Update Alchemy entry on Indexers page — Stellar Data API is now live

[kaankacar]

The Indexers overview listed Alchemy as "most popular choice on Ethereum; now in talks to expand their service to Stellar, with a targeted launch in the first half of 2026." That's out of date — Alchemy's Stellar Data API is live.

This updates the entry to describe the actual offering: indexed transfer history, account balances, and NFT holdings across native, Stellar Classic, and Soroban assets (queryable without running your own indexer), and links Alchemy's Stellar Data API overview. It also cross-links Alchemy's Stellar JSON-RPC and the existing RPC providers entry, since Alchemy offers both the Chain/RPC API and the (indexer-style) Data API.

Sourced from Alchemy's own docs.

🤖 Generated with Claude Code

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Demo replay of stellar#2573 (original author: mmazco) — seeded for the triage-agent demo.

[github-actions]

READY-FOR-HUMAN-APPROVAL

Checked: gh pr view/gh pr diff (1 file, +1/-1, docs/data/indexers/README.mdx), the current RPC providers table, and terminology usage elsewhere in docs/.

Mechanics

• ✓ Link style: uses a relative link (../apis/rpc/providers.mdx) per repo convention, not an absolute developers.stellar.org URL.
• ✓ Relative link target exists and resolves correctly (docs/data/apis/rpc/providers.mdx).
• ✓ No new images, so no alt-text concerns.
• ✓ No heading changes.
• ✓ No obvious typos/grammar issues in the new prose.

Technical accuracy

• ✓ Cross-link claim verified: Alchemy is indeed listed in the RPC providers table (docs/data/apis/rpc/providers.mdx:25), so "Alchemy also provides Stellar JSON-RPC and appears in the RPC providers list" is accurate as of this checkout.
• ✓ "Stellar Classic" / "Soroban" / "native" asset terminology is consistent with usage elsewhere in the docs (e.g. docs/tokens/token-interface.mdx, docs/build/guides/basics/classic-transition.mdx).
• ⚠ I can't verify the specific Alchemy API implementation details (indexed transfer history / account balances / NFT holdings coverage, "opaque pageKey pagination") against Alchemy's actual docs from this checkout — I don't have web access in this review pass. The PR description says it's sourced from Alchemy's own docs; a maintainer should spot-check the linked page before merging, since this is the kind of "wrong endpoint/feature" claim that'd be P1 if inaccurate.
• Note: this replaces a dated/speculative claim ("in talks... targeted launch in the first half of 2026") with a live-product claim — if Alchemy's launch status turns out to still be misrepresented, this would need re-editing, not just a revert.

Non-blocking nits

• The new bullet goes into more implementation-level detail (request body format, pagination mechanism) than the other entries in this "Portfolio APIs" list, which stay at a product-description level (e.g. Goldsky, Mercury, OBSRVR). Maintainers may want to trim to match the section's altitude, but this is a style call, not a blocker.
• Does not reference or close any open issue in this repo — the PR body labels itself a demo replay of an external PR (stellar/stellar-docs#2573), not tied to a tracked issue here.

Given the substantive rewrite (new external links + specific product-behavior claims, not just a typo/version-string swap), this doesn't fit the trivial auto-merge tier — leaving unlabeled for a maintainer to confirm the Alchemy-specific claims before merge.