Resemble AI Text-to-Speech API vs Smallest.ai Lightning TTS

Resemble AI Text-to-Speech API 0

No x402, MPP or L402 (0). The per-second prices ($0.00067 on Flex, $0.0005 on Team and Business) were read on 30 September from app.resemble.ai/billing/api/v1/plans, a billing data endpoint this run doesn't read, so that reading is struck, and the pricing pages can't be re-read under the terms, so no per-unit price stands today (0). No free synthesis allowance per the 1 October check (0). A person signs up in a browser (0).

Smallest.ai Lightning TTS 40

No x402, MPP or L402 (0). Per-character prices for both models published without a login (20). Pay as you go starts with $10 of trial credits, which the terms also describe, and no page says a card is needed to claim them, read as inworld-tts's free plan was (20). A person signs up in a browser at app.smallest.ai and creates the key in the dashboard, and top-ups go to a card on file (0). Total 40.

Resemble AI Text-to-Speech API 31

Read as a model. The newest changelog entry is 2026-06-30 per the 1 October check, not re-read on 4 November (terms), 127 days old (10). No dated entries in the last 90 days that we could read (0 of 10). Older models were deprecated on 2026-06-29 and the docs say voices on them can't generate until upgraded, with no effective date published (0 of 10). Public changelog and a support address, SDK issue trackers not checked (8 of 25). The Node SDK clone on 4 November still ends at 754a91e (6 April 2026, 3.5.3); Python 1.9.0 of 6 April per the 1 October check, not re-read. Neither has a release since the June model changes (10 of 15). The Python SDK still declares support from Python 3.6, and the Node repository has no CI workflow and no release tags (3 of 10).

Smallest.ai Lightning TTS 68

Read as a model. The newest Lightning changelog entry is dated 2 November 2026 (the v3.1 retirement notice), after a preview checkpoint on 29 October (30). Dated Lightning entries on 10, 23 and 28 August, 29 September, 14, 17 and 29 October and 2 November count, less 5 for churn, because the default model retires 28 days after its notice and clones made on it stop working (15 of 20). Public changelog, email support and a Discord server, with no evidence read of how they answer (10 of 15). The Python SDK smallestai 5.14.0 dates from 7 October, but the npm Node SDK has not been published since May 2025 (8 of 15). The Python SDK repository runs CI and release workflows, but has no licence file (5 of 10). Total 68.

Resemble AI Text-to-Speech API 46

API reading of the checklist. WAV or MP3 from 8 to 48 kHz at 16, 24 or 32-bit, but synchronous synthesis returns the whole clip as base64 inside JSON (18 of 25). 2,000 characters per synchronous or HTTP stream request, 3,000 per WebSocket message. Longer scripts go through projects and clips (10 of 20). Errors are a boolean and a message, with advice to log the request ID (5 of 20). No retry, idempotency or billing-on-failure guidance found (0 of 20). Two required fields, a voice UUID and the text, and SDKs in Node and Python (13 of 15). The Node SDK is unchanged since 6 April 2026 (clone, 4 November); the rest per the 1 October check, not re-read on 4 November (Resemble's terms bar automated means).

Smallest.ai Lightning TTS 72

API reading of the checklist. Eight output formats, a choice of sample rate and word timestamps only when asked (22 of 25). Voices are listed per model and the docs say they filter by language and accent. Paging wasn't confirmed (14 of 20). Errors carry error and message fields with a shared status-code guide, without TTS-specific codes (14 of 20). Synthesis is stateless and request_id is echoed for correlation, but there is no idempotency key and billing of a retried request isn't stated (10 of 20). Two required fields, text and voice_id, but the default model retires on 30 November. Official Python and Node SDKs, with the Node SDK last published in May 2025 (12 of 15). Total 72.

Resemble AI Text-to-Speech API 75

Checkly status page with a Resemble Ultra HTTP check under Text-To-Speech and an activity history (20). One TTS event in the last 90 days, a 1-minute check failure on 22 September, and 100 per cent uptime on that check over 90 days. The page monitors HTTP synthesis only, not the WebSocket (30). 40 requests a second per token published, with WebSocket connection limits in the docs (15). No 429 behaviour or retry guidance found (0). No SLA found (0). Resemble Ultra is the current GA model (10). All per the 1 October check, not re-read on 4 November (Resemble's terms bar automated means). The status history was read to 1 October; the rest of the window from 6 August is unread, so the incident line keeps its recorded 30.

Smallest.ai Lightning TTS 58

BetterStack status page at status.smallest.ai with components for the Global, India and USA APIs (one health check covers the Agents and Models APIs), docs, the app and Electron, and per-component history (20). In the 90 days from 8 August the health checks on the shared API failed in all three regions on 9, 10, 13, 14 and 15 September (about 8, 21, 33, 17 and 64 minutes of flapping), in the Global and India regions on 11 and 17 September (12 minutes each), and in the USA region alone on 1, 3, 5, 12, 21 and 30 September (6 to 62 minutes) and 6 October (12 minutes). Outages in every region at once are read as wide errors, so several majors (0). Limits are published with numbers but disagree. The limits page says one TTS request at a time per account with up to five sockets, the Lightning v3.1 Pro card says 10 concurrent and the pricing page says 15 streams and 100 requests a minute on pay as you go (8 of 15). 429 is documented with exponential backoff from 500 ms to 30 s and Retry-After when present, and the limits page tells clients to expect 429s at the concurrency ceiling (15). An infrastructure SLA of 99.99 per cent is named for Enterprise only, with no terms, and the terms disclaim any availability commitment (5 of 10). lightning_v3.1_pro is stable and only the dated checkpoint is preview (10). 20 + 0 + 8 + 15 + 5 + 10 = 58.

Resemble AI Text-to-Speech API 75

OpenAPI file in JSON and YAML at docs.resemble.ai (25). llms.txt with Markdown pages (10). The docs separate synchronous, HTTP streaming and WebSocket synthesis and say WebSocket needs Business, but rarely say when not to use one (12 of 20). Request bodies typed in the spec. The model is chosen by the voice, not the request (12 of 15). Examples on each endpoint, but the errors page only describes success: false with a message and lists no status codes (6 of 15). /api/v2 paths and a dated product changelog shared with detection (10 of 15). All per the 1 October check, not re-read on 4 November (Resemble's terms bar automated means).

Smallest.ai Lightning TTS 92

OpenAPI 3.1 for the sync and SSE routes and AsyncAPI 2.6 for the WebSocket, with request and event schemas (25). llms.txt and a Markdown copy of every page (10). A transport guide, model cards and the compare page say which model and transport suit which job, but changelog entries correct the language lists and enums the docs and spec carried (15 of 20). Typed fields with enums for model, sample rate, language and output format, an 8,000-character limit and pattern rules on session_id and request_id (14 of 15). Examples in curl, Python and JavaScript, with error bodies on the reference and a shared error page (13 of 15). Versioned /v1 paths, a dated Lightning changelog and dated preview checkpoints (15). Total 92.

Resemble AI Text-to-Speech API 65

Closed service with clear terms (15 of 30). The privacy policy gives retention periods and links a sub-processor list, but names Google Cloud, Render and Cerebrium as infrastructure while the changelog calls Resemble Ultra xAI-powered, and no xAI processing is mentioned (15 of 30). Deprecation started on a dated changelog entry (29 June 2026), with no end-of-life date or policy (5 of 20). The voice cloning listing gives 10 for the same entry and its model versions page reading. That split is left for a re-read. US hosting with named regions and UK processing for Enterprise on request, sub-processor list at trust.resemble.ai (15 of 20). All per the 1 October check, not re-read on 4 November (Resemble's terms bar automated means); the terms of 14 August 2026 were re-read on 4 November.

Smallest.ai Lightning TTS 70

Closed service with clear terms naming Smallest Inc. under California law (15). The ZDR page is specific about what each mode keeps, but the terms' no-training clause and the privacy policy's machine-learning use of usage data sit side by side, the privacy policy gives no retention periods, and the policy doesn't mention the DPA a footer link points to (15 of 30). A deprecations page gives statuses, dates and migration steps, and earlier models answer 410 with a pointer. The notice for the default lightning_v3.1, dated 2 November, gives 28 days before voices change and v3.1 clones stop working, and the terms let Smallest discontinue services without notice (12 of 20). Two regions named (Mumbai and Oregon) with region-pinned hosts, and only Google Analytics and Fullstory named among third parties, with no sub-processor list found (10 of 20). Total 52.