Serverless agent event backbone (queue/bus)
Need durable delayed HTTP callbacks, fan-out, or a real message fabric for agents — not a workflow runtime.
At a glance — Oct 2026
Updated 2026-10-27 · forward this page: /jtbds/serverless-agent-queue#briefScores as of 2026-09-14 (43 days old; Depot marks scores stale after 30 days). The pick is still Depot's current editorial pick; it has not been re-reviewed since. Prices below carry their own dates.
- Depot Pick
- Upstash QStash · 8.38/10 for this job (curated estimate, high confidence)
DX + pricePerf for a bus that agents can fire-and-forget. Distinct from durable-agent-workflows (Temporal/Inngest steps) and event-driven-agent-jobs (Inngest DX default).
- Runner-up
- Inngest · 8.07/10
- When not to use the pick
- Need durable multi-step state/retries as code — Inngest/Temporal; need NATS subjects/leaf nodes — Synadia; need Kafka protocol/replay — WarpStream (or Confluent if that's already standard).
- Lock-in / migration
- The pick has lower stored lock-in risk than runner-up Inngest (3.5 vs 4.2).
- Sourced price (no comparable unit)
Pick: no sourced price in this job's unit (no_matching_sourced_price).
No cheapest SKU (no_candidate_has_sourced_price_in_job_unit:queue_message). No price was invented.
- Free option
- Upstash QStash Free plan (free) — source, as of 2026-10-21
- Failure modes to watch
- Partial tool success: Require a per-item status and a failure count. Success for the task requires the failed count to be zero or explicitly handed to a retry queue.
- Inter-agent misalignment: Log the assigned subtask next to the worker's stated result. The lead rejects a result that does not match the assignment.
- Non-determinism: Run the task more than once and compare the end state, not a single transcript. Record the trial count next to any success rate you cite.
- Observability gap: Alert on a drop in trace ingestion and on certificate expiry for the trace host. Do not treat a missing trace as a successful quiet run.
- Runaway spend: Set a budget and a tool-call cap per task. Alert when spend jumps. Stop the run at the cap instead of summarizing a partial trace as success.
- Tool loop: Hash the last several tool names and arguments. Stop when the same call repeats and the observation did not change. Cap tool calls per task.
Cite: Agent Provider Depot, Depot Pick for serverless-agent-queue: upstash-qstash, scores as of 2026-09-14. Agents: GET /api/decide?jtbd=serverless-agent-queue
Free Serverless agent event backbone (queue/bus) options · for scheduled-ops agents
Upstash QStash
DX + pricePerf for a bus that agents can fire-and-forget. Distinct from durable-agent-workflows (Temporal/Inngest steps) and event-driven-agent-jobs (Inngest DX default).
Pricing (directional): As of 2026-09-14 (upstash.com/pricing/qstash): Free 1k messages/day, 50 GB, 1 MB max. PAYG $1 per 100k messages (unlimited/day, 10 MB, 1-year delay); bandwidth free to 50 GB then $0.05/GB. Fixed 1M $180/mo; Fixed 10M $420/mo; Enterprise cus…
Lock-in risk: higher = more lock-in (worse). Overall already inverts this dimension.
Depot pick for a raw serverless agent event backbone (webhooks, delayed retries, fan-out) without operating Kafka/SQS. Inngest when you need durable steps; NATS/Synadia when you need a real messaging fabric; WarpStream/Confluent when you already are Kafka.
Quote for Serverless agent event backbone (queue/bus)
Depot Pick stays Upstash QStash. Prices below are sourced SKU rows only (as of 2026-10-27). Input and output are not blended. GET /api/quote?jtbd=serverless-agent-queue
Nothing was compared. mixed_units: usd_per_100k_messages and usd_per_million_events are both stored. They were not ranked together and were not converted. Monthly plans were not included. cheapest stays null. pickIsPriceWinner is null.
- Pay as You Go bandwidth usd_per_gb $0.05 source as of 2026-10-03
- Fixed 10M usd_per_month $420 source as of 2026-10-03
- Fixed 1M usd_per_month $180 source as of 2026-10-03
- Free usd_per_month $0 source as of 2026-10-03
- Pay as You Go messages usd_per_100k_messages $1 source as of 2026-10-03
8 of 10 candidates have no sourced price row. 10 are excluded from the USD per 100k messages comparison (queue_message). mixed_units: usd_per_100k_messages and usd_per_million_events are both stored. They were not ranked together and were not converted. Monthly plans were not included. cheapest stays null.
Runners-up
Inngest
Best DX default for durable agent workflows in TypeScript/Python. Temporal when you need harder multi-lang…
Synadia Cloud (NATS)
Pick when agents need a real pub/sub fabric (multi-service, edge leafs) not just HTTP callbacks. QStash for…
WarpStream
Pick when the agent backbone must be Kafka-protocol (replay, consumers, Iceberg) without Confluent prices…
Amazon SQS
Hyperscaler queue leaf when already on AWS. QStash remains Depot serverless HTTP bus default; SQS when…
Amazon EventBridge
AWS event backbone for agents (webhooks via API destinations, cron via Scheduler). Inngest/Temporal for…
Azure Service Bus
Azure twin to SQS/EventBridge for agent queues when already on Azure. EventBridge remains AWS hyperscaler…
When NOT to use the top pick
Need durable multi-step state/retries as code — Inngest/Temporal; need NATS subjects/leaf nodes — Synadia; need Kafka protocol/replay — WarpStream (or Confluent if that's already standard).
Full ranking (score table)
Ranked with this JTBD's weights. Scores are curated estimates unless marked otherwise. Agents: prefer /api/decide then this table for tie-breaks.
| # | Provider | Overall | Fit | $/perf | Latency | DX | As of |
|---|---|---|---|---|---|---|---|
| 1 | WarpStream | 8.4 | 8.8 | 9.0 | 8.6 | 7.8 | 2026-09-14 |
| 2 | Upstash QStashDepot Pick | 8.4 | 8.2 | 9.2 | 8.4 | 9.2 | 2026-09-14 |
| 3 | Synadia Cloud (NATS) | 8.3 | 8.6 | 8.2 | 8.8 | 8.0 | 2026-09-14 |
| 4 | Google Cloud Pub/Sub | 8.1 | 8.2 | 8.2 | 9.2 | 7.6 | 2026-09-14 |
| 5 | Inngest | 8.1 | 8.2 | 8.0 | 8.4 | 9.0 | 2026-09-14 |
| 6 | Azure Service Bus | 8.0 | 8.6 | 7.5 | 9.2 | 7.2 | 2026-09-14 |
| 7 | Amazon SQS | 8.0 | 7.8 | 8.8 | 9.2 | 7.0 | 2026-09-14 |
| 8 | Amazon EventBridge | 8.0 | 8.4 | 7.8 | 9.2 | 7.4 | 2026-09-14 |
| 9 | Confluent Cloud | 8.0 | 9.2 | 5.8 | 9.4 | 7.5 | 2026-09-14 |
| 10 | Trigger.dev | 7.8 | 7.8 | 8.2 | 8.0 | 9.2 | 2026-09-14 |
Score methodology for this job
DX + pricePerf for a bus that agents can fire-and-forget. Distinct from durable-agent-workflows (Temporal/Inngest steps) and event-driven-agent-jobs (Inngest DX default).
capabilityFit: 25%pricePerformance: 18%latencyReliability: 15%developerDx: 15%privacyPosture: 10%lockInRisk: 7%maturity: 10%