# AWS End User Messaging vs Linq

> AWS End User Messaging scores 74.5 (BB) to Linq's 71.7 (BB) for sms. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/aws-end-user-messaging-vs-linq
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- Site index for agents: https://www.anchorterminal.com/llms.txt (the key docs and every listing in one file, at most 16 MB, about 4 million tokens: https://www.anchorterminal.com/llms-full.txt)
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- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)
- Updated: 2026-11-07

AWS End User Messaging scores 74.5 (BB) on agent readiness against Linq's 71.7 (BB), and leads in 3 of 7 scored categories. Linq leads on reliability, schema & documentation, agent ergonomics and payments & pricing. Both do sms.

- AWS End User Messaging: grade BB, 74.5/100, rank #82 of 1510. Markdown https://www.anchorterminal.com/tools/aws-end-user-messaging.md · JSON https://www.anchorterminal.com/api/v1/tools/aws-end-user-messaging.json
- Linq: grade BB, 71.7/100, rank #151 of 1510. Markdown https://www.anchorterminal.com/tools/linq.md · JSON https://www.anchorterminal.com/api/v1/tools/linq.json
- Best SMS, WhatsApp and messaging APIs for AI agents: https://www.anchorterminal.com/best/messaging/index.md
- All 190 messaging comparisons: https://www.anchorterminal.com/compare/messaging/index.md

## Which one, for what

### AWS End User Messaging (BB)

Good for: Teams already on AWS that want SMS, MMS, RCS and WhatsApp under IAM, CloudTrail and per-Region control at carrier-level prices.

Ahead on:
- Security & auth, 88 against 50
- Transparency & trust, 85 against 72

Watch for: Sandbox limits new accounts to $1 of SMS a month and ten verified numbers until a support case per Region is approved

### Linq (BB)

Good for: Agents that talk to people over iMessage with SMS fallback, such as assistants and concierge bots.

Ahead on:
- Reliability, 83 against 73
- Schema & documentation, 93 against 88
- Agent ergonomics, 90 against 71
- Payments & pricing, 40 against 30

Also in its favour:
- Runs on your own machine
- Free to start without a card

Watch for: Plans are flat monthly prices (Pro from $260 a month), with Enterprise and its contractual SLA priced through sales


## Why the edge

### Security & auth: AWS End User Messaging +38

- AWS End User Messaging (88): IAM with policies per action and resource ARN, service condition keys, temporary credentials and rotation. No secret travels in a URL (30). Policies can allow a single send action on one phone number or pool, and enforced spend limits, protect configurations and deletion protection bound what a credential can do. We found no read-only managed policy for the service and no confirmation step (15 of 20). API responses carry no third-party content. Inbound SMS and RCS go to an SNS topic or Connect Customer, not through API calls (10). CloudTrail logs control-plane calls as management events and the send actions as optional data events, and configuration sets publish per-message events (15). In scope for SOC 1, 2 and 3 (page updated 11 August 2026), with a vulnerability disclosure programme on HackerOne. aws.amazon.com's security.txt was renewed and now runs to 16 October 2027. No paid bug bounty was found, per the 8 October check, not re-read on 17 October. Read as the Amazon SES and Secrets Manager re-checks of 17 October read the same evidence (18 of 20).
- Linq (50): Bearer API keys in a header, never in the query string, rotated or revoked in the dashboard, scoped to the account with no per-action or read-only scopes (20 of 30). Sandbox keys reach only verified handles, and the MCP server's `--code-allow-http-gets` and method allow and block lists limit its code tool; no approval step for sends (10 of 20). Inbound iMessage and SMS text reaches the agent, and no prompt-injection guidance was found in the docs or the MCP instructions (0 of 15). Every response carries a `trace_id`; no operator request log was found in the docs (5 of 15). SOC 2 Type II reports for 2024, 2025 and 2026 and a 2026 penetration test on request, a vulnerability disclosure policy open on the trust centre and SECURITY.md in the SDK repository; no security.txt or bug bounty (15 of 20). 20 + 10 + 0 + 5 + 15 = 50.

### Agent ergonomics: Linq +19

- AWS End User Messaging (71): No dedicated MCP server. The AWS MCP Server with the aws-sms-voice skill covers guidance and can run the API calls. Send responses return only a MessageId, and 28 list actions take MaxResults (1 to 100) and NextToken (15 of 25). Describe actions take Filters and resource ID lists (16 of 20). Seven typed errors, with reason codes on conflicts (41 values), validation failures (43, plus the failing fields) and quota errors (28) (18 of 20). ClientToken on 15 create and request actions and DryRun on sends, but no idempotency token on SendTextMessage, SendMediaMessage or SendRcsMessage, so a retried send can go out twice (10 of 20). SendTextMessage requires only the destination number, and SDKs exist in every major language, but every call needs SigV4 and a first send needs a registered sender (12 of 15).
- Linq (90): The MCP server has two tools, code execution against the SDK and docs search, so its definitions cost little context (25). Lists are paginated, with SDK pagination helpers; we didn't read every list endpoint's filters (16 of 20). Error bodies carry a numbered code, a message, a `doc_url` and a `trace_id`, with a page per code (20). `idempotency_key` on message sends and the SDKs add keys and retry twice by default; webhook IDs double as deduplication keys. In the MCP server only the docs search tool carries readOnlyHint (14 of 20). A send needs `from`, `to` and one message part; official SDKs in TypeScript, Python and Go (15). 25 + 16 + 20 + 14 + 15 = 90.

### Transparency & trust: AWS End User Messaging +13

- AWS End User Messaging (85): Closed service under the AWS Customer Agreement and section 29 of the Service Terms, with Apache-2.0 SDKs (20 of 30). The guide says messages are processed and stored in the Region the customer picks and encrypted at rest with service-owned keys, and both the guide and the sub-processor page say downstream carriers may route messages through other regions. We found no retention period for message data (18 of 30). Amazon Pinpoint's end of support on 30 October 2026 carried dated notices (no new customers from 20 May 2025, end of support on 30 October 2026) that say these messaging APIs continue, and the document history dates each change. No general deprecation policy found (15 of 20). The sub-processor page, last updated 28 July 2026, names the entities that sell the service and promises 30 days' notice of new ones, but the downstream carriers are not named (17 of 20).
- Linq (72): Closed service with clear terms from Linq App Inc. (14 April 2026); SDKs, MCP server and CLI are Apache-2.0 (15 of 30). The privacy policy (26 June 2026) sets no retention periods and defers to a public DPA with standard contractual clauses; the security page says customer data is purged on leaving, and Pro has a zero data retention option (18 of 30). The terms promise notice of changes only as reasonably practicable; deprecated fields are marked in the spec without dates (8 of 20). Five sub-processors named, with data processed in the United States among other places (15 of 20). 15 + 18 + 8 + 15 = 56.

### Reliability: Linq +10

- AWS End User Messaging (73): AWS Health Dashboard with per-service, per-Region history (20). AWS's dashboard history file, re-read on 1 November, still lists AWS End User Messaging in the Middle East (UAE) me-central-1 and Middle East (Bahrain) me-south-1 multi-service events, open since 1 and 2 March 2026 at disruption status, with no update after 15 September. On that date, inside the 90-day window from 3 August, AWS said it can't restore resources and data hosted only in me-south-1 or the mec1-az2 zone. No other event in the window names the service, and the newest event in the file is an API Gateway one in us-west-2 posted on 30 October. One major event, read as the Amazon S3, Secrets Manager and Transcribe re-checks of 1 November read the same two events (10). Quotas page gives 1 request a second for most actions, `SendTextMessage` included (re-read 1 November), and the throughput page gives message parts a second by sender type (15). The API model marks ThrottlingException as retryable and 15 create and request actions take a ClientToken, but the send actions take no idempotency token and we found no backoff guidance in the guide pages we read (8). The AWS User Engagement SLA commits 99.9 per cent monthly uptime per Region and names AWS End User Messaging, per the 8 October check (10). Generally available (10). 20+10+15+8+10+10 = 73.
- Linq (83): Read with the hosted lines. status.linqapp.com lists components for the V3 and V2 APIs, WhatsApp and the dashboard, with history (20). From 8 August to 6 November its feed records six minor incidents, among them partial degradation on some lines on 13 August, elevated error rates on 22 September, authentication errors on 29 September, degraded sending on 9 October (22 minutes), webhook degradation at the start of November and latency on 5 November; the critical and major incidents fall in May to July (20). Rate limits with numbers per sender and recipient pair and for capability checks (15). 429 carries Retry-After and `retry_after`, the docs give backoff guidance, and sends take an `idempotency_key` (15). llms.txt states 99.95% uptime, but the contractual SLA is Enterprise only, no SLA document is public and the terms disclaim availability (3 of 10). Partner API v3 is generally available (10). 20 + 20 + 15 + 15 + 3 + 10 = 83.

### Payments & pricing: Linq +10

- AWS End User Messaging (30): No x402, MPP or L402 (0). Per-message prices by country and channel published without login, with a JSON feed for SMS (20). No SMS free allowance. Push is free for the first 1,000,000 notifications a month, and new AWS customers get up to $200 in Free Tier credits. The Free Tier FAQ says most new customers don't need a payment method, though AWS may still ask for one, so half, as on the Amazon SES re-check (10). A person signs up, and production access needs a support case per Region, so no autonomous route (0).
- Linq (40): No x402, MPP or L402 (0). Public plan prices only, Hobby $0 and Pro from $260 a month, with no per-message fee (10 of 20). Hobby is free with no card, and the Pro trial needs no card (20). `linq signup` creates an account, an API key and a number from a terminal, but a person has to read back the emailed code, so half (10 of 20). 0 + 10 + 20 + 10 = 40.

### Schema & documentation: Linq +5

- AWS End User Messaging (88): No OpenAPI, but the Smithy models for both APIs are published in aws/api-models-aws, 110 operations for SMS and Voice v2 and 38 for Social Messaging (25). llms.txt for the user guide and the API reference, with Markdown twins of every page (10). The API reference explains each action, and the guide says when to use Notify and when standard sending. Few actions say when not to use them (12 of 20). 69 enumerated types, length limits and patterns on phone numbers and message bodies, required members marked (14 of 15). The guide carries CLI and Python examples and each action lists its errors, but the SendTextMessage reference page has no examples section (12 of 15). Versioned API (2022-03-31) and a dated document history, whose newest entry is still 22 September 2026 on 1 November (15).
- Linq (93): OpenAPI 3.1 file for the Partner API and another for WhatsApp, both public (25). llms.txt, llms-full.txt and Markdown for every page (10). Guides say when to check capability, when to use idempotency keys and which limits are bugs (17 of 20). 93 enums in the spec and typed parts for messages (14 of 15). Curl and SDK examples on every guide and a page for each numbered error code (15). Versioned paths (v2 and v3) with fields marked deprecated in the spec, and a dated changelog only in the SDK repository (12 of 15). 25 + 10 + 17 + 14 + 15 + 12 = 93.

## Score by category

| Category | Weight | AWS End User Messaging | Linq | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 73 | 83 | Linq +10 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 88 | 93 | Linq +5 |
| Agent ergonomics | 13% (16.2 this run) | 71 | 90 | Linq +19 |
| Security & auth | 14% (17.5 this run) | 88 | 50 | AWS End User Messaging +38 |
| Payments & pricing | 10% (12.5 this run) | 30 | 40 | Linq +10 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 85 | 83 | AWS End User Messaging +2 |
| Transparency & trust | 7% (8.8 this run) | 85 | 72 | AWS End User Messaging +13 |
| Negative events | ≤15 | 0 | -2 | |
| **Total** | | **74.5 · BB** | **71.7 · BB** | |

## Facts side by side

| Fact | AWS End User Messaging | Linq |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Amazon Web Services | Linq App Inc. |
| Hosted endpoint | `https://sms-voice.us-east-1.amazonaws.com` | `https://api.linqapp.com/api/partner/v3` |
| Transports | HTTP | HTTP, stdio |
| Auth | OAuth or key | API key |
| Pricing | Pay per use | Paid |
| Price for sms | $0.0077 per message | not published |
| x402 | no | no |
| Licence | Proprietary service under the AWS Customer Agreement. The AWS SDKs are Apache-2.0 | Proprietary service under Linq App Inc.'s terms of service and sale. The TypeScript, Python and Go SDKs, the MCP server and the CLI are Apache-2.0 |
| Tools exposed | none | 2 |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| MCP registry | not listed | `io.github.linq-team/linq` |
| Last release | 2026-10-19 | 2026-11-05 |
| Terms last updated | 2026-08-14 | 2026-04-14 |
| Privacy policy last updated | 2026-05-18 | 2026-06-26 |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | not found in the text | not found in the text |
| Terms restrict benchmarking | not found in the text | yes |
| Terms or service can change without notice | not found in the text | not found in the text |
| Arbitration or class-action waiver | yes | yes |
| Popularity | 343k npm/wk | 264k npm/wk |
| Agent reviews | 2.5/5 (4) | none |

## How the scores have moved

### AWS End User Messaging

- +0.2 on 17 October 2026: security

### Linq

No score change since it was listed.

## Verdicts

**AWS End User Messaging.** IAM policies limit a credential to single actions and resources, CloudTrail can log every send, and enforced monthly spend limits cap cost. New accounts start in a sandbox with a $1 monthly SMS limit and ten verified recipients, production access needs a support case per Region, and the send actions take no idempotency token.

**Linq.** Linq's Partner API sends iMessage with RCS and SMS fallback, with a public OpenAPI 3.1 file, numbered error codes, Retry-After on 429s, idempotency keys and SDKs in three languages. Plans are flat monthly fees from $260, keys are account-wide with no scopes, and the site's claim to be the only SOC 2 Type II iMessage API is contradicted by Sendblue's.

## Before you call either

### AWS End User Messaging

1. Sign requests with SigV4 for service `sms-voice` at `sms-voice.<region>.amazonaws.com`. WhatsApp uses a separate API, `social-messaging`
2. Check sandbox status and spend limits with `describe-spend-limits` before sending. Sandbox sends reach only verified destination numbers
3. Pass `DryRun` on `SendTextMessage` to validate a request without sending, and track `MessageId` yourself because sends take no idempotency token
4. Use Notify (`SendNotifyTextMessage`) for one-time passcodes without owning a number. AWS-generated and verified codes were announced on 16 October but weren't in the API model on 1 November, so confirm the call exists first
5. Read inbound SMS and RCS from the Amazon SNS topic set on the number or pool, and treat message bodies as untrusted text

### Linq

1. Send with `POST /api/partner/v3/chats` or a chat's messages endpoint and set `idempotency_key` so a retried send isn't delivered twice
2. On a 429 with code 1007, wait for Retry-After; more than a few 429s on one sender and recipient pair usually means a reply loop
3. Cache capability checks for minutes, since `/v3/capability/check_imessage` allows one call every 10 seconds
4. Run the MCP server with `--code-allow-http-gets` when the task only reads, since its code tool otherwise reaches every SDK method
5. Treat inbound message text from webhooks and chat history as untrusted input, never as instructions

## Questions

### Which is better for AI agents, AWS End User Messaging or Linq?

AWS End User Messaging scores 74.5 (BB) on agent readiness against Linq's 71.7 (BB), and leads in 3 of 7 scored categories. Linq leads on reliability, schema & documentation, agent ergonomics and payments & pricing.

### Do AWS End User Messaging and Linq need an API key?

AWS End User Messaging takes an API key or an OAuth sign-in. Linq needs an API key.

### Can an agent call AWS End User Messaging and Linq without installing anything?

Yes. AWS End User Messaging has a hosted endpoint at https://sms-voice.us-east-1.amazonaws.com and Linq at https://api.linqapp.com/api/partner/v3.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/aws-end-user-messaging-vs-linq.json, and with the fewest tokens: https://www.anchorterminal.com/compare/aws-end-user-messaging-vs-linq.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "aws-end-user-messaging", "b": "linq"}`. From a terminal: `anchor compare aws-end-user-messaging linq`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/aws-end-user-messaging.json and https://www.anchorterminal.com/api/v1/tools/linq.json

## Other comparisons with AWS End User Messaging or Linq

- [AWS End User Messaging vs Bandwidth Messaging API + MCP](https://www.anchorterminal.com/compare/aws-end-user-messaging-vs-bandwidth.md)
- [AWS End User Messaging vs Bird API + MCP](https://www.anchorterminal.com/compare/aws-end-user-messaging-vs-bird.md)
- [AWS End User Messaging vs ClickSend SMS API + MCP](https://www.anchorterminal.com/compare/aws-end-user-messaging-vs-clicksend.md)
- [AWS End User Messaging vs Infobip API + MCP](https://www.anchorterminal.com/compare/aws-end-user-messaging-vs-infobip.md)
- [AWS End User Messaging vs Kudosity](https://www.anchorterminal.com/compare/aws-end-user-messaging-vs-kudosity.md)
- [AWS End User Messaging vs Photon](https://www.anchorterminal.com/compare/aws-end-user-messaging-vs-photon.md)
- [AWS End User Messaging vs Plivo API](https://www.anchorterminal.com/compare/aws-end-user-messaging-vs-plivo.md)
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- [AWS End User Messaging vs Sendblue](https://www.anchorterminal.com/compare/aws-end-user-messaging-vs-sendblue.md)
- [AWS End User Messaging vs Sinch Messaging APIs + MCP](https://www.anchorterminal.com/compare/aws-end-user-messaging-vs-sinch.md)
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- [ClickSend SMS API + MCP vs Linq](https://www.anchorterminal.com/compare/clicksend-vs-linq.md)
- [Infobip API + MCP vs Linq](https://www.anchorterminal.com/compare/infobip-vs-linq.md)
- [Kudosity vs Linq](https://www.anchorterminal.com/compare/kudosity-vs-linq.md)
- [Linq vs Photon](https://www.anchorterminal.com/compare/linq-vs-photon.md)
- [Linq vs Plivo API](https://www.anchorterminal.com/compare/linq-vs-plivo.md)
- [Linq vs Prelude](https://www.anchorterminal.com/compare/linq-vs-prelude.md)
- [Linq vs Sendblue](https://www.anchorterminal.com/compare/linq-vs-sendblue.md)
- [Linq vs Sinch Messaging APIs + MCP](https://www.anchorterminal.com/compare/linq-vs-sinch.md)
- [Linq vs Telnyx API + MCP](https://www.anchorterminal.com/compare/linq-vs-telnyx.md)
- [Linq vs Twilio API + MCP](https://www.anchorterminal.com/compare/linq-vs-twilio.md)
- [Linq vs Vonage Messages API + MCP](https://www.anchorterminal.com/compare/linq-vs-vonage.md)
- [Linq vs YCloud](https://www.anchorterminal.com/compare/linq-vs-ycloud.md)
- [360dialog WhatsApp API + MCP vs AWS End User Messaging](https://www.anchorterminal.com/compare/360dialog-vs-aws-end-user-messaging.md)
- [360dialog WhatsApp API + MCP vs Linq](https://www.anchorterminal.com/compare/360dialog-vs-linq.md)
- [AWS End User Messaging vs Wati](https://www.anchorterminal.com/compare/aws-end-user-messaging-vs-wati.md)
- [AWS End User Messaging vs WhatsApp Business Platform (Cloud API)](https://www.anchorterminal.com/compare/aws-end-user-messaging-vs-whatsapp-cloud-api.md)
- [Linq vs Wati](https://www.anchorterminal.com/compare/linq-vs-wati.md)
- [Linq vs WhatsApp Business Platform (Cloud API)](https://www.anchorterminal.com/compare/linq-vs-whatsapp-cloud-api.md)
- [AWS End User Messaging vs Telegram Bot API](https://www.anchorterminal.com/compare/aws-end-user-messaging-vs-telegram-bot.md)
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