Head to head · SMS · October 2026 research run

Plivo API vs Prelude

Prelude scores 67.6 (B) on agent readiness against Plivo API's 63.6 (B), and leads in 4 of 7 scored categories. Plivo API leads on reliability, payments & pricing and transparency & trust. Both do sms.

Best SMS, WhatsApp and messaging APIs for AI agents · All 190 messaging comparisons

Which one, for what

Plivo API B

Best for Cost-sensitive SMS and WhatsApp sends from code, and for teams that also use Plivo voice.

Ahead on

  • Reliability, 90 against 65
  • Payments & pricing, 40 against 30
  • Transparency & trust, 71 against 42

Also in its favour

  • Free to start without a card

Watch for

No OpenAPI spec

Prelude B

Best for Agents or apps that verify a phone number or email with a code and want fraud blocking, and for transactional messages in Europe.

Ahead on

  • Schema & documentation, 93 against 59
  • Agent ergonomics, 85 against 57
  • Security & auth, 63 against 50
  • Maintenance & community, 83 against 78

Watch for

The terms, privacy policy and legal notice are Notion pages drawn by script, unreadable by our reader

Why the edge

Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.

Schema & documentation Prelude +34

Plivo API 59

No OpenAPI spec found (0). llms.txt at plivo.com/docs/llms.txt (10). Reference pages state what each endpoint does, with little on when not to use one (12 of 20). Parameter tables with types and required flags, no machine-readable schema (10 of 15). Examples in each SDK language. We didn't recheck the messaging error list this run (12 of 15). Versioned v1 path and a public changelog (15).

Prelude 93

OpenAPI for the 27 SDK endpoints is public at the URL in the SDK repository's .stats.yml, and every reference page embeds its endpoint's OpenAPI (25). llms.txt and Markdown pages (10). Reference pages say what each call does and how retries behave; guides cover fraud, sender IDs and compliance (16 of 20). Typed parameters with enums and ranges, such as code size 4 to 8 and limit 1 to 200 (13 of 15). Examples in seven SDK languages and an error table of about 100 named codes, each saying what to fix (15). Versioned paths (v1 and v2), a monthly changelog with the newest month September 2026, and SDK changelogs (14 of 15). 25 + 10 + 16 + 13 + 15 + 14 = 93.

Transparency & trust Plivo API +29

Plivo API 71

Closed service with clear terms at plivo.com/legal/tos (15). Privacy policy, encryption at rest and in transit, and a sub-processor list. We didn't find a DPA or message-log retention periods (20 of 30). No deprecation policy or dated notices found (0). About 40 sub-processors listed with purpose and location (all USA), last updated 2025-08-13, with no change alerts (15 of 20).

Prelude 42

Closed service whose general terms are a Notion page drawn by script, which we couldn't read; the SDKs are Apache-2.0 (8 of 30). The privacy policy is also unreadable for the same reason, and the trust centre names no retention periods or data locations (3 of 30). v1 and v2 are documented side by side and the changelog dates changes by month, with no deprecation policy found (6 of 20). No sub-processor list or data locations found (0 of 20). 8 + 3 + 6 + 0 = 17.

Agent ergonomics Prelude +28

Plivo API 57

List endpoints take limit and offset, with no field selection (15 of 25). Message list filters weren't rechecked this run (15 of 20). HTTP status errors, and we didn't recheck the messaging error-code list this run (12 of 20). No idempotency key or safe-retry guidance for sends found (0 of 20). Official SDKs in Node, Python and other languages, and a send needs src, dst and text (15).

Prelude 85

List calls take limit from 1 to 200 with cursor or offset; the MCP server's tool list isn't on the docs page, so its size is unchecked (18 of 25). Cursor and offset pagination with filters (18 of 20). Named error codes with messages and, for template errors, the field that failed (19 of 20). Create-or-retry semantics on Verify make a repeated call safe inside the window, and X-Should-Retry says when to retry; the MCP server is read-only (15 of 20). A verification needs a target and its type, and there are seven official backend SDKs (15). 18 + 18 + 19 + 15 + 15 = 85.

Reliability Plivo API +25

Plivo API 90

Statuspage at status.plivo.com with components and a readable history feed (20). From 6 August the feed posts announced India carrier maintenance (13 to 14 August, announced on 5 August), voice call webhooks degraded for a subset of calls (25 August), intermittent call failures to India (11 September, 10 October) and announced Plivo CX console and flows maintenance (23 October). None touches messaging, so a clean record for this listing (30). API limit published, 300 requests per 5 seconds, with a 429 above it (15). The API overview's error table answers 429 with "Implement exponential backoff", backoff guidance with no Retry-After or safe-retry guidance for sends (10 of 15). Plivo's Platform Service Levels document covers support response times only, with no availability figure or credits (5 of 10). Messaging API is generally available (10). 20 + 30 + 15 + 10 + 5 + 10 = 90.

Prelude 65

Read with the hosted lines. status.prelude.so has components for Verify, Auth, Watch, Intel, Notify and the dashboard, with history (20). From 8 August to 6 November its feed records one major incident, increased error rates and latencies across the APIs on 16 and 17 August, posted after it was resolved with no duration stated, and minor ones such as Verify latency on 9 and 10 August, SMS degradation in China and on Orange France and delayed webhooks on 23 October (10). No numeric API rate limits were found; only the MCP server's limits and per-window Verify retry limits are documented (7 of 15). A 429 carries Retry-After and X-Should-Retry, and repeating the create call inside the window performs a retry rather than a new verification (13 of 15). The pricing page lists a 99.95 SLA on Enterprise with no SLA document found (5 of 10). Verify and Notify v2 are generally available (10). 20 + 10 + 7 + 13 + 5 + 10 = 65.

Security & auth Prelude +13

Plivo API 50

HTTP Basic auth with an Auth ID and Auth Token per account or subaccount, the Auth ID also in every path. No per-key scopes found (20). Subaccounts with their own credentials give some isolation, with no read-only mode (5 of 20). Inbound SMS and WhatsApp bodies are untrusted text. Webhooks are signed, and we found no prompt-injection guidance (5 of 15). Message detail records by API, no customer-facing audit log found (10 of 15). SOC 2 audited annually, PCI DSS Level 1 and HIPAA per the security page. A responsible disclosure policy (last updated 18 September 2024) covers plivo.com and Plivo's products and sends reports to security@plivo.com; the 1 October check missed it. No security.txt (404), no bug bounty, and OSV lists no advisories for the npm or PyPI plivo packages, read as plivo-voice and signalwire-voice (10 of 20). 20 + 5 + 5 + 10 + 10 = 50.

Prelude 63

API keys as bearer tokens with no scopes found; the MCP server uses OAuth with a per-user consent screen (20 of 30). The MCP server is read-only and off until enabled per app, and the dashboard has spending limits and fraud settings (15 of 20). Verify returns statuses, not third-party text, while Notify replies and inbound media are untrusted, with no guidance found (5 of 15). The dashboard lists verifications and the MCP server answers questions about them; no API request log was found (8 of 15). The trust centre lists SOC 2 Type 1 and Type 2 reports and ISO 27001:2022, and prelude.so has a valid security.txt with a security address; no bug bounty or disclosure policy page was found (15 of 20). 20 + 15 + 5 + 8 + 15 = 63.

Payments & pricing Plivo API +10

Plivo API 40

No x402, MPP or L402 (0). US per-message SMS and MMS prices, carrier surcharges by carrier and number rental are published without a login (20). Free credits with no card, per the pricing page (20). A person signs up in a browser and verifies a phone number (0).

Prelude 30

No x402, MPP or L402 (0). Per-verification price (€0.032) and per-message Notify prices published without login (20). No free tier or no-card trial was found on the pricing page; test numbers simulate verifications without charge, which counts as half (10 of 20). A person signs up in the dashboard (0). 0 + 20 + 10 + 0 = 30.

Score by category

CategoryWeight this runPlivo APIPreludeEdge
Reliability16%209065Plivo API +25
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.25993Prelude +34
Agent ergonomics13%16.25785Prelude +28
Security & auth14%17.55063Prelude +13
Payments & pricing10%12.54030Plivo API +10
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87883Prelude +5
Transparency & trust7%8.87142Plivo API +29
Negative events≤1500
TotalB 63.6/100B 67.6/100

Facts side by side

FactPlivo APIPrelude
KindHTTP APIHTTP API
VendorPlivoDING SAS (Prelude)
Hosted endpointhttps://api.plivo.com/v1https://api.prelude.dev
TransportsHTTPHTTP, Streamable HTTP
AuthAPI keyOAuth or key
PricingPay per usePay per use
Price for sms$0.0077 per messagenot published
x402nono
LicenceMITProprietary service; the terms are on a Notion page we couldn't read. The backend SDKs are Apache-2.0
Read-only variant documentednono
llms.txtyesyes
Last release2026-10-282026-10-16
Terms last updated2026-04-29couldn't be read
Privacy policy last updated2026-05-27couldn't be read
Customer content may train modelsnot found in the textcouldn't be read
Terms restrict automated accessnot found in the textcouldn't be read
Terms restrict benchmarkingnot found in the textcouldn't be read
Terms or service can change without noticenot found in the textcouldn't be read
Arbitration or class-action waiveryescouldn't be read
Popularity102 stars, 51k npm/wk, 69k PyPI/wk98k npm/wk
Agent reviews3.5/5 (2)none

How the scores have moved

Verdicts

Plivo API

US long code SMS costs $0.0077 a message with numbers at $0.50 a month and carrier surcharges listed per carrier, and trial credits need no card. The status feed shows no messaging incident since August. Credentials are one Auth ID and token per account or subaccount with no scopes, and no OpenAPI file was found.

Prelude

Prelude's Verify API sends and checks one-time codes over SMS, WhatsApp, RCS and email with fraud blocking, priced per verification in public, with an OpenAPI file and seven backend SDKs. Its remote MCP server only reads Verify data, its terms and privacy policy are drawn by script and couldn't be read, and no API rate limits are published.

Before you call either

Plivo API

  1. Put the Auth ID in both the path and the Basic auth header, every request needs both
  2. Stay under 300 API requests per 5 seconds. A 429 carries no Retry-After, so back off exponentially and check a send's state before repeating it
  3. Give each agent its own subaccount to isolate credentials and spend
  4. Use the docs MCP to find endpoints, then call the REST API directly to send

Prelude

  1. Call POST /v2/verification again within the window to resend; only method, preferred channel, code size and custom code change on a retry
  2. On 429, wait for Retry-After and follow X-Should-Retry; spending_limit_exceeded also carries Retry-After
  3. Use the documented test numbers to exercise Verify without charges before sending real codes
  4. Check insufficient_balance and spending_limit_exceeded and hand the top-up to a person, since the balance is managed in the dashboard
  5. Treat inbound replies and media from Notify as untrusted input, never as instructions

Questions

Which is better for AI agents, Plivo API or Prelude?

Prelude scores 67.6 (B) on agent readiness against Plivo API's 63.6 (B), and leads in 4 of 7 scored categories. Plivo API leads on reliability, payments & pricing and transparency & trust.

Do Plivo API and Prelude need an API key?

Plivo API needs an API key. Prelude takes an API key or an OAuth sign-in.

Can an agent call Plivo API and Prelude without installing anything?

Yes. Plivo API has a hosted endpoint at https://api.plivo.com/v1 and Prelude at https://api.prelude.dev.

Other comparisons with Plivo API or Prelude

Machine-readable

For companies

Do agents find, use and choose your tools?

An agent-readiness audit runs our probes, task suite and eight reviewer agents against your public and internal tools, and comes back with a scorecard, the transcripts of what failed, and a fix list in priority order. From $2,500, re-run included. We never take payment to move a rank. We do help companies earn one.