OfflineTTS vs Amazon Polly: Free Local TTS vs AWS Cloud

Amazon Polly is an AWS text-to-speech service designed for application integration. OfflineTTS is a no-account browser application that uses the user’s device for speech inference. The important difference is not a winner badge: Polly provides a managed API, AWS controls, SSML, and speech marks; OfflineTTS provides interactive local-capable workflows without an OfflineTTS subscription or per-character meter.

Quick Comparison

Question	OfflineTTS	Amazon Polly
Product model	Browser tool	Managed AWS API
Current OfflineTTS charge	No account, subscription, API key, or per-character charge	AWS usage and account terms apply
Text processing	Depends on engine and language	Sent to the configured Polly endpoint
Cached operation	Supported local paths after assets load	Requests need AWS service connectivity
Control	Plain text, punctuation, speed, voice	SSML, lexicons, speech marks, SDK parameters
Integration	End-user browser workflow; no hosted public API	REST operations, AWS SDKs, batch tasks
Output	WAV and MP3 in the current app	Formats and sample rates supported by Polly APIs
Practical limit	50,000-character app workflow plus device resources	AWS quotas, request limits, and account configuration

Pricing: Local Resources vs AWS Metering

OfflineTTS does not currently charge for generated characters. That is not the same as a zero-cost production system: the user supplies model bandwidth, browser storage, CPU or GPU time, electricity, battery, and the human time needed to check audio. Long input is also divided into reviewable work within the application’s current 50,000-character cap.

Amazon Polly’s official pricing page separates Standard, Neural, Long-Form, and Generative voices. As reviewed on August 1, 2026, the published US public rates outside applicable free usage were $4, $16, $100, and $30 per million characters respectively. The page also lists class-specific free usage and explains the newer AWS Free Tier credit program. Region, GovCloud, taxes, other AWS services, storage, transfer, and architecture costs can change the total.

Do not use a single “Polly costs $4 per million” statement for every project. Select the exact voice class and region, determine whether speech marks are also requested, include every revision, and confirm the current official page. For OfflineTTS, include local operational cost and review time in the same worksheet.

Voice Quality Requires the Same Script

Polly voice classes use different synthesis systems and do not all have the same language, region, or feature coverage. OfflineTTS also combines separate engines: Kokoro, Piper, Kitten, and Supertonic. A catalog count or model family does not establish how either option will read a project’s proper names, acronyms, decimals, dates, code-switching, or specialist terminology.

Prepare a representative 150–250 word passage and use the intended voice, language, and default settings in both systems. Keep playback level consistent. Record lexical errors separately from personal style preference, then repeat with a multi-paragraph passage to test long-form joins and pacing. OfflineTTS catalog grades are internal discovery labels, not standardized scores, and AWS product names are not cross-provider listening grades.

Polly may be the better fit when a team values centrally configured voices, predictable API integration, and documented AWS operations. OfflineTTS may fit an individual who wants a local-capable interactive tool and can manually review exports. Neither choice makes a script factually correct or publication-ready.

Privacy and Offline Boundaries

Polly is a cloud service: application text is sent to the selected AWS endpoint for synthesis under the customer’s AWS configuration, agreement, region, logging, security, and retention controls. That is not evidence that AWS mishandles text; it means the organization must evaluate the managed-service data flow and configure it appropriately.

OfflineTTS audio inference runs in the browser. English Kokoro text preparation can run locally after required assets load, and Supertonic provides local text preparation for its supported languages. Supported non-English Kokoro text uses the OfflineTTS phonemization endpoint before browser synthesis. Website hosting, analytics, initial model downloads, browser storage, downloaded files, and third-party links remain separate data paths described in the Privacy Policy.

For confidential, regulated, or privileged content, test with harmless placeholder text and map both workflows. A local architecture can reduce external content transfer, but it does not supply an AWS compliance report, business associate agreement, data-processing agreement, device management, or legal approval. A managed AWS service can offer enterprise controls while still requiring network content processing. Choose from the actual policy and contract requirements.

SSML, Lexicons, and Speech Marks

Polly supports a documented subset of SSML, pronunciation lexicons, and speech marks. Speech marks can describe word and sentence boundaries or visemes for synchronization workflows. Support varies by voice and feature, so validate every tag against AWS’s current supported-tags table; do not assume that all W3C SSML elements or Polly voices accept the same combination.

OfflineTTS accepts ordinary text rather than a Polly SSML document. Punctuation and the speed control affect delivery, and optional timing uses a separate post-generation alignment workflow. That timing is not the same artifact as Polly speech marks. If a production system depends on phoneme tags, managed lexicons, visemes, or deterministic event metadata, Polly has the more relevant interface.

API and Operations

Amazon Polly exposes AWS API operations and SDK support and can participate in services built around IAM, queues, functions, object storage, monitoring, and regional deployment. Teams still need to design retries, quotas, error handling, idempotency, storage, access control, cost alarms, and deletion. A managed synthesis endpoint does not remove application engineering.

OfflineTTS is an end-user website, not a hosted public synthesis API or service-level agreement. Developers who need automation should evaluate upstream engines directly, pin versions, review model licenses, and build their own job controls. Scraping the web interface or depending on internal asset URLs is not a stable integration contract.

Decision Guide for Amazon Polly Workloads

Choose OfflineTTS when the tested voice and language meet the need, a user-operated browser workflow is acceptable, local-capable processing matters, and manual export and review fit the project. Choose Polly when the application needs AWS-native authentication, managed endpoints, SSML or lexicons, speech marks, service quotas, and programmatic integration.

For an audiobook, compare pronunciation and long-form continuity, then include editing and mastering in the decision. For e-learning, include terminology review, captions, accessible controls, and course packaging. For an enterprise application, include contracts, identity and access management, monitoring, regional requirements, and total architecture cost. The correct result can differ by workload even inside one organization.

Verification Snapshot for Amazon Polly

This comparison was materially reviewed on August 1, 2026 against Amazon’s official pricing and developer documentation and the current OfflineTTS interface. The AWS page was treated as authoritative for voice-class rates and free-usage language; subjective voice claims were deliberately left to a same-script listening test.

Before purchase or launch, re-open the linked AWS pages, select the exact region and voice class, and calculate a month that includes revisions and speech-mark requests. Recheck the OfflineTTS engine-language notice with a network panel and test cached operation on the target browser. Record the date, settings, script, and observed errors so the decision remains reproducible after either product changes.

Try the OfflineTTS browser workflow →